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Lifestyle intervention for improving school achievement in overweight or obese children and adolescents

  1. Anne Martin1,*,
  2. David H Saunders1,
  3. Susan D. Shenkin2,
  4. John Sproule1

Editorial Group: Cochrane Developmental, Psychosocial and Learning Problems Group

Published Online: 14 MAR 2014

Assessed as up-to-date: 8 MAY 2013

DOI: 10.1002/14651858.CD009728.pub2


How to Cite

Martin A, Saunders DH, Shenkin SD, Sproule J. Lifestyle intervention for improving school achievement in overweight or obese children and adolescents. Cochrane Database of Systematic Reviews 2014, Issue 3. Art. No.: CD009728. DOI: 10.1002/14651858.CD009728.pub2.

Author Information

  1. 1

    Institute for Sport, Physical Education and Health Sciences (SPEHS), University of Edinburgh, Moray House School of Education, Edinburgh, UK

  2. 2

    University of Edinburgh, School of Clinical Sciences and Community Health, Edinburgh, UK

*Anne Martin, Moray House School of Education, Institute for Sport, Physical Education and Health Sciences (SPEHS), University of Edinburgh, Holyrood Road, Edinburgh, EH8 8AQ, UK. a.martin-19@sms.ed.ac.uk.

Publication History

  1. Publication Status: New
  2. Published Online: 14 MAR 2014

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Summary of findings    [Explanations]

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms

 
Summary of findings for the main comparison. Lifestyle interventions versus standard care for improving school achievement—Findings after sensitivity analysis

Lifestyle interventions versus standard care for improving school achievement in overweight or obese children and adolescents

Patient or population: overweight or obese children and adolescents
Settings: overweight or obese child and youth population
Intervention: lifestyle intervention
Comparison: standard care

OutcomesIllustrative comparative risks* (95% CI)Relative effect
(95% CI)
No. of participants
(studies)
Quality of the evidence
(GRADE)
Comments

Assumed riskCorresponding risk

Standard careLifestyle intervention

Overall school achievement
Grade point average obtained from school records Scale from zero to 100
Follow-up: mean two years
Mean overall school achievement in the control groups was
-2.64 average points
Mean overall school achievement in the intervention groups was
1.78 higher
(0.8 to 2.76 higher)
321
(one study1)
⊕⊕⊕⊝
moderate2

Mathematics achievement
Woodcock-Johnson Tests of Achievement III

Scale from zero to 200
Follow-up: mean 13 weeks
Mean mathematics achievement in the control groups was
104 points
Mean mathematics achievement in the intervention groups was
three higher
(0.78 to 5.22 higher)
96
(one study1)
⊕⊕⊕⊕
high

Language achievement
CAT-3—Canadian Achievement Test, version 3

Scale from zero to 1000
Follow-up: mean one year
Mean language achievement in the control groups was
583.67 points
Mean language achievement in the intervention groups was
27.97 higher
(5.35 lower to 61.29 higher)
73
(one study)
⊕⊝⊝⊝
very low2,3,4

Reading achievement
Woodcock-Johnson Tests of Achievement III
Follow-up: mean 13 weeks
Mean reading achievement in the control groups was
100 points
Mean reading achievement in the intervention groups was
0.0 higher
(2.21 lower to 2.21 higher)
96
(one study)
⊕⊕⊕⊕
high

Writing achievementStudy populationNot estimablezero
(zero)
See commentNo evidence available

See commentSee comment

Moderate


Vocabulary achievement
Peabody Picture Vocabulary Test, version 3

Scale from zero to 200
Follow-up: mean 24 weeks
Mean vocabulary achievement in the control groups was
84.17 points
Mean vocabulary achievement in the intervention groups was
1.19 higher
(4.04 lower to 6.42 higher)
80
(one study)
⊕⊕⊝⊝
low2,4

Special education classStudy populationNot estimablezero
(zero)
See commentNo evidence available

See commentSee comment

Moderate


*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI).
CI: Confidence interval; RR: Risk ratio.

GRADE Working Group grades of evidence.
High quality: Further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: We are very uncertain about the estimate.

 1Findings are presented after a sensitivity analysis has been carried out. High risk of bias and differences in intervention type and duration were suspected to have influenced the finding substantially; thus findings of the sensitivity analysis are presented in this table.
2Intervention was aimed at the general population (normal weight and overweight/obese), not at overweight/obese children only.
3Study had a high risk of attrition bias.
4Study included only a few participants, which resulted in a wide confidence interval.

 Summary of findings 2 Lifestyle interventions versus standard care for improving school achievement—Findings before sensitivity analysis

 

Background

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms
 

Description of the condition

Overweight and obesity are conditions of excessive body fat accumulation. In clinical practice, paediatric overweight and obesity are commonly identified by age- and gender-specific body mass index (BMI) percentiles, BMI standard deviation scores, BMI cutoffs and waist circumference (WC) percentiles relative to a reference population (Reilly 2010; Rolland-Cachera 2011).

The primary criteria used to define overweight and obesity include:

  1. overweight: BMI or WC ≥ 85th percentile to 95th percentile, BMI > +one standard deviation of the average; and
  2. obesity: BMI or WC > 95th percentile, BMI > +two standard deviations of the average.

Also, BMI cutoffs from the International Obesity Task Force (IOTF) are often used as a definition of overweight and obesity. These age-specific BMI cutoffs were constructed to match the definition of overweight and obesity in adults (BMI ≥ 25 kg/m2 and BMI ≥ 30 kg/m2, respectively) (Cole 2000). Recently, the IOTF BMI cutoffs were reformulated to allow BMI to be expressed as standard deviation or percentile (Cole 2012).

These criteria are used to define overweight and obesity in this review.

In 2010, the World Health Organization (WHO) estimated that more than 40 million children younger than five years of age were overweight worldwide (WHO 2012). In the USA, the prevalence of overweight and obese children and adolescents (aged two to 19 years) was 32% (Ogden 2010). Results of UK surveys indicate that 33% of children in their final year of primary school are overweight or obese (NHS 2010). Childhood obesity prevalence is increasing in middle- and low-income countries, for example, up to 40% of children in Mexico are overweight and obese, 32% in Lebanon and 28% in Argentina (Gupta 2012).

Childhood obesity is associated with adverse health consequences, including atherosclerosis, hypertension, type 2 diabetes, fatty liver disease and the metabolic syndrome (Calcaterra 2008; Daniels 2009). Co-morbid health problems are common in obese children and include psychosocial disorders (e.g. depression, anxiety), respiratory disorders (e.g. obstructive sleep apnoea) and skeletal disorders (e.g. musculoskeletal discomfort) (Han 2010; Puder 2010).

Interest is growing in the connection between increased body fatness and children’s brain health, cognitive function and related attainments such as educational achievement and future socioeconomic success (Geddes 2010).

In terms of cognitive function, evidence from systematic reviews and meta-analyses indicates that overweight or obese children of primary school age have a significantly lower full intelligence quotient (IQ) (eight studies; N = 1086) and performance IQ (four studies; N = 536) compared with children of normal weight (Yu 2010). A recent systematic review, which included observational studies of children and adolescents up to 18 years of age, concluded that consistent evidence suggests a negative association between overweight or obesity and executive function, attention and visuospatial skills (39 studies; N = 16,112), that is, overweight or obese children score less well on some cognitive tests (Liang 2013).

In terms of school achievement, a systematic review of cross-sectional and longitudinal studies (29 studies; study population ranged from N = 259 to N = 60,252) concluded that childhood obesity is weakly associated with lower educational achievement (Caird 2011). However, this association was further weakened when confounding variables such as socioeconomic status were controlled. Findings of a prospective cohort study (N = 2582, follow-up six years) indicate that 'growing out of obesity' was associated with improved mathematics achievement after adjustments for confounding variables compared with maintaining normal body weight status (Carter 2010). This finding suggests that interventions for reducing child and youth obesity may have beneficial effects on school achievement.

In terms of future 'success', a Finnish longitudinal study (N = 9754, follow-up 17 years) suggested that adolescent obesity predicts unemployment in later life, with educational achievement as a mediating factor (Laitinen 2002). A British birth cohort study (N = 12,537) indicated that adolescent obesity (at age 16 years) is associated with fewer years of schooling and predicts lower income in young female adults (at age 23 years), including those who are no longer obese (Sargent 1994). These findings were further confirmed by Han 2011, using the National Longitudinal Survey of Youth 1979 (N = 1974, follow-up 12 to 16 years), and by Sabia 2012, using the National Longitudinal Study of Adolescent Health (N = 12,445, follow-up 13 years). Findings from the National Longitudinal Survey of Youth 1997 (N = 8427, follow-up eight years) suggest that obese adolescents had a 39% lower chance of obtaining a college degree than peers of normal weight (Fowler-Brown 2010). All of these studies accounted for a variety of confounding variables, including measures of socioeconomic status (e.g. parental education, household income).

These sources of evidence are based on observational data. This suggests that data are vulnerable to confounding even when some confounders are measured and accounted for; it also suggests that causal effects cannot be inferred. Reverse causation is possible, whereby children with poorer baseline cognitive ability or educational achievement are more likely to be obese. However, these data do allow one to hypothesise that interventions that reduce body weight might provide a range of additional benefits.

 

Description of the intervention

A lifestyle intervention aims to modify individuals' way of living and improve their health by changing patterns of behaviour that are harmful to health (WHO 1998). A lifestyle intervention for obese people targets dietary patterns, physical activity, sedentary behaviour and behaviour patterns. Clinical guidelines for prevention and treatment of childhood obesity from countries such as the UK (NICE 2013; SIGN 2010), Australia (NHMRC 2003), Canada (Lau 2007) and Malaysia (Ismail 2004) recommend a multicomponent approach that combines:

  1. reduced energy intake;
  2. increased physical activity (≥ 60 minutes/d, moderate to vigorous intensity);
  3. decreased sedentary behaviour (e.g. screen time less than two hours/d); and
  4. behaviour change techniques (e.g. goal setting, self monitoring, self regulation).

A Cochrane review concluded that lifestyle interventions aiming to alter eating habits, sedentary behaviour and physical activity patterns in a family-based setting were effective in achieving clinically meaningful weight reduction in children (Oude Luttikhuis 2009).

 

How the intervention might work

 

Effects in the general child and adolescent population

Multicomponent lifestyle interventions may benefit cognitive function and school achievement in the general population, that is, a study population that includes both children and adolescents of normal weight and those who are overweight or obese. For example, after implementation of an uncontrolled intervention involving healthy nutrition, physical activity and behaviour change techniques in a US primary school, an upward trend in reading performance scores was noted; these scores exceeded the national average by 10% after eight years (Nansel 2009). Another uncontrolled study implementing a healthy diet and physical activity programme in a primary school reported an increase in the numbers of children passing standardised tests in writing, reading and mathematics by 25%, 27% and 31%, respectively (Sibley 2008). A similar but controlled school-based intervention promoting healthy eating and physical activity behaviour in children 11 to 14 years of age led to significant improvement in mathematics, listening and speaking scores after only five weeks compared with the control condition (standard classroom education) (Shilts 2009).

 

Aspects of lifestyle interventions

 

Dietary modification

Composition of the diet may impact cognition and educational achievement by altering neurotrophic and neuroendocrine factors involved in learning and memory. These are decreased by high-energy diets containing saturated fat and simple sugars, and they are increased by diets that are rich in omega-3 polyunsaturated fatty acids and micronutrients (Gomez-Pinilla 2008; Kanoski 2011). Longitudinal data suggest that diets high in fat and sugar in preschool children (N = 3966; age three to four years) are associated with decreased intelligence and school performance at primary school age (Feinstein 2008; Northstone 2011). A controlled healthy school meal intervention over three years in more than 80,000 children led to improved mathematics, English and science achievement (Belot 2011). Therefore, an improvement in dietary quality could have beneficial effects even without weight loss.

 

Increased physical activity

Physical activity may affect cognitive function and academic achievement through physiological mechanisms (elevated blood circulation, increased levels of neurotrophins and neurotransmitters) (Dishman 2006), learning and developmental mechanisms (children’s movement experience stimulates the processing of other concepts) (Piaget 1956).

A meta-analysis of 44 experimental and cross-sectional studies (in children aged four to 18 years) indicated that increased physical activity caused significant overall improvement in cognitive function and school performance (effect size 0.32; standard deviation (SD) 0.27) (Sibley 2003). A systematic review suggests that school-based physical activity interventions (32 studies; N ˜ 3762; in children five to 18 years of age) may enhance both cognitive and school performance (CDC 2010). Therefore, physical activity might also benefit overweight and obese children independent of weight loss.

 

Reduced sedentary behaviour

A sedentary lifestyle in children, particularly television viewing ≥ two hours/d, is associated with the development of overweight or obesity (review of 71 studies; Rey-Lopez 2008) and may replace opportunities to engage in activities that promote scholastic and cognitive development. Longitudinal data indicate that children (younger than three years of age) with low television exposure (< three hours/d) performed better than those with high television exposure (≥ three hours/d) in reading (N = 1031) and mathematics (N = 1797) (Peabody Individual Achievement Test) when at preschool age (Zimmerman 2005). Similarly, parent-reported television viewing in preschool children was inversely related to mathematics achievement at age 10 years (N = 1314) (Pagani 2010) and reading achievement at age 10 to 12 years (N = 308) (Ennemoser 2007). Longer-term educational outcomes may also be affected. Hancox 2005 indicated that young people (N = 980; follow-up 21 years) with the highest television viewing time during childhood and adolescence tended to have no formal educational qualifications, and those with a university degree watched the least television (TV) during childhood and adolescence. Television viewing ≥ three hours/d at age 14 years (N = 678) was associated with a two-fold risk to fail to obtain a post–secondary school education at 33 years of age compared with those watching television < one hour/d, mediated by attention difficulties, frequent failure to complete homework and negative attitudes about school at 16 years of age (Johnson 2007). Therefore, reducing sedentary behaviour (TV and screen time, sitting time) in obese or overweight children might improve cognitive function and school achievement.

 

Behaviour modification

Behaviour change techniques in overweight and obese children may foster decision making and self control skills needed to increase energy expenditure and reduce energy intake (Bruce 2011); they also may benefit studying and thus educational achievement.

The effects of multicomponent lifestyle interventions or their individual components on cognitive function and school achievement might be influenced by study design characteristics (e.g. intervention type, dose and duration) and participant characteristics that determine physical and mental development and maturation (e.g. age, gender, weight status).

In summary, lifestyle interventions could act, alone or in combination, through numerous plausible mechanisms of action to benefit cognitive function, school achievement and future success (Figure 1).

 FigureFigure 1. Potential causal links between overweight or obesity and impaired cognitive function, school achievement and future success. Reverse causation may also occur when cognitive function, school achievement and future success can impact the 'mediating factors', and both in turn may cause worsening of overweight and obesity.

 

Effects in overweight and obese children and adolescents

Overweight and obesity are associated with poor cognitive function, school achievement and future success (Caird 2011; Sabia 2012; Sargent 1994; Yu 2010); therefore lifestyle interventions that reduce overweight and obesity (Oude Luttikhuis 2009) might also benefit cognitive function and school achievement. Mechanisms explaining how lifestyle interventions could benefit overweight and obese children differently from the general population build on suggestive evidence from observational and experimental studies. These include neurocognitive, psychosocial and pathophysiological mechanisms associated with the development and consequences of childhood obesity.

Research indicates that overweight and obese children show higher impulsivity and inattention and lower reward sensitivity, self regulation and mental flexibility compared with peers of normal weight (Delgado-Rico 2012a; Fields 2013; Nederkoorn 2006). These neurocognitive factors are associated with increased food intake and uncontrolled eating behaviour, and thus are assumed to be predictors of weight gain (Fields 2013; Francis 2009). Lifestyle interventions for weight management might positively impact the neurocognitive factors required for controlled food intake. A randomised controlled trial conducted in 44 overweight and obese children (eight to 14 years of age) suggested that specific training of self regulatory abilities improved weight loss maintenance after an in-patient weight loss programme in the intervention group compared with the control group (Verbeken 2013). Findings from another randomised controlled overweight treatment programme involving 62 children (mean age 10.3 ± 1.1 years) showed improved problem-solving skills after an intervention duration of six months (Epstein 2000). Inhibition control skills were improved in 42 obese adolescents from 12 to 17 years of age after 12 weeks of cognitive-behavioural therapy (Delgado-Rico 2012b).

In comparison with normal weight children and youth, overweight and obese peers more often experience psychosocial distress through weight-related teasing, discrimination and social isolation; this can result in impaired self esteem, self efficacy and quality of life as well as depression (Brixval 2012; Danielsen 2012; Griffiths 2010; Puhl 2007). Overweight-related teasing and social rejection are associated with low school performance in overweight or obese children (Gunnarsdottir 2012a; Krukowski 2009). Psychosocial effects of overweight and obesity are suspected to mediate the inverse association between overweight and school performance (Caird 2011). Lifestyle interventions for paediatric overweight treatments might benefit school achievement through improvement of self esteem, depressive symptoms and quality of life (Oude Luttikhuis 2009; Pratt 2013).

Child and youth obesity is associated with co-morbidities, such as hypertension, impaired insulin sensitivity and metabolic syndrome, which are known to be inversely related to cognitive function and academic achievement (i.e. children with hypertension, insulin resistance and metabolic syndrome have lower cognitive and academic test scores than those without these co-morbidities) (Lande 2012; Yau 2012). Health problems may also cause overweight and obese children to miss school more often (Pan 2013); higher levels of school absenteeism are associated with lower performance in school (Gottfried 2011). Research indicates that childhood obesity is also associated with sleep deprivation and disrupted sleep due to obesity-related disordered breathing (Chen 2008; Spruyt 2012). Poor sleep may reduce the ability to concentrate in school (Beebe 2010) and impacts negatively on cognitive function and school achievement (Beebe 2010; Pérez-Chada 2009; Spruyt 2012). Lifestyle interventions can improve health and reduce co-morbidities in children (Oude Luttikhuis 2009), and thus may benefit cognitive and educational outcomes.

Lifestyle interventions for weight management could improve cognitive and school performance by reducing sources of metabolic and psychosocial stress, and by improving those neurocognitive abilities associated with weight gain. With increasing adiposity, the severity of neurocognitive, psychosocial and pathophysiological changes might increase, and the benefits of lifestyle interventions for weight management, as seen in school, cognitive and later life outcomes, might depend on the level of adiposity. Lifestyle interventions may benefit cognitive function, school and later life achievement through different obesity-related pathways (Figure 1); therefore it is plausible that overweight and obese children benefit more strongly than normal weight children from the effects of improved diet, physical activity and sedentary behaviour.

 

Why it is important to do this review

The current rising trend in childhood obesity (WHO 2012) means that the prevalence of cognitive and educational problems among children is also likely to increase. Given evidence of a link between low school achievement and economic disadvantage, this might have financial repercussions as regards future employability and income.

The beneficial effects of changes in diet, physical activity, sedentary behaviour and thinking patterns for prevention and treatment of childhood obesity are well established (Oude Luttikhuis 2009; Waters 2011) and are reflected in clinical guidelines for the management of obesity (Ismail 2004; Lau 2007; NHMRC 2003; NICE 2013; SIGN 2010). However, the extent to which these lifestyle interventions might affect cognitive function and subsequent school and later life achievement of overweight and obese children and adolescents remains unknown. Drawing from neurocognitive, psychosocial and pathophysiological aspects of causes and consequences of childhood obesity, lifestyle interventions for weight management might benefit overweight and obese children differently compared with normal weight children through modification of obesity-related conditions unlikely to be present in normal weight children (see How the intervention might work).

It is important that researchers, as well as government agencies, educators and parents and guardians, work together to improve children’s physical and mental health. This review is important, as it may influence the way in which existing health promotion policies for schools are monitored and evaluated. This review identified interventions most likely to yield benefits and assessed the likely extent of potential benefits. It may emphasise a reevaluation of policies and implementation of more effective interventions to improve the development, health and well-being of children and adolescents.

 

Objectives

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms

To assess whether lifestyle interventions (in the areas of diet, physical activity, sedentary behaviour and behavioural therapy) improve school achievement, cognitive function and future success in overweight or obese children and adolescents compared with standard care, waiting list control, no treatment or attention control.

 

Methods

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms
 

Criteria for considering studies for this review

 

Types of studies

Randomised controlled trials (RCTs), cluster-randomised trials and controlled clinical trials (CCTs), with or without cross-over design, were eligible for inclusion. For inclusion of cross-over trials, data from the first iteration had to be obtainable.

 

Types of participants

Overweight or obese children and adolescents aged three to 18 years attending preschool or school, and whose body weight status was determined using age- and gender-specific BMI percentiles, BMI z-scores, BMI standard deviation scores (SDSs), BMI cutoff points or waist circumference. Classification of weight status needed to be based on a relevant national or international reference population for inclusion.

We did not exclude studies on the basis of location.

We excluded children with medical conditions known to affect weight status and academic achievement, such as Prader-Willi syndrome and diagnosed intellectual disabilities.

 

Types of interventions

Studies were eligible for inclusion when the interventions provided aimed to prevent or reduce childhood obesity. For inclusion, interventions had to be lifestyle interventions of any frequency and duration provided in any setting that comprised one or more of the following.

  1. Interventions to increase physical activity (including exercise).
  2. Dietary and nutritional interventions (excluding supplements).
  3. Interventions to decrease sedentary behaviour, screen time and TV time.
  4. Psychological interventions to facilitate weight management.

Interventions could target children with or without the participation of family members.

We excluded pharmacological and surgical interventions because these interventions are likely to be conducted in a less representative sample, thus limiting generalisability.

Eligible control interventions were waiting list, attention control, no treatment and standard care.

 

Types of outcome measures

Primary and secondary outcomes did not serve as criteria for selection of studies based on title and abstract. Assessment of outcome measures was a criterion for inclusion in this review when full texts were screened. We extracted outcome data at the end of the intervention and at any other follow-up time point.

 

Primary outcomes

  1. School achievement (DoE 2010), recorded by appropriately trained investigators (e.g. teachers, researchers). Participant- and parent-reported data were excluded.  
    1. Overall school performance.
      1. Average of school subject performance over one academic year, for example, grade point average (GPA).
    2. Individual subject performances.
      1. School participant percentage scores or standard achievement test scores for (a) math, (b) reading or (c) language.
      2. Validated tests for school achievement in math, reading or language, for example, Woodcock-Johnson Tests of Achievement III.
    3. Special education classes.
      1. Need for special education class.
      2. Reduction of time allocated for special education class.

These primary outcomes were used for the 'Summary of findings' table.

 

Secondary outcomes

  1. Cognitive function (Carroll 1993): measures of general cognitive ability or different cognitive domains (e.g. attention, memory, executive function) assessed using validated cognitive ability tests administered by appropriately trained investigators. We excluded participant-reported and parent-reported data.
  2. Future success (Geddes 2010): includes, but is not limited to, total years of schooling, high school completion, enrolment in higher education, rates of full-time employment, monthly earnings, home ownership, receipt of social services obtained from administrative records and self reports.
  3. Obesity indices: age- and gender-specific BMI, BMI z-scores and BMI-SDSs when obtained from measured (not self reported) weight and height, measured waist circumference and measures of body fatness by dual-energy x-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA). Studies reporting obesity indices were included only when measures of school achievement, cognitive function and/or future success were also reported. Inclusion of these data might enable the review authors to examine whether any changes in school performance, cognitive function and/or future success variables occur independently of changes in obesity (see How the intervention might work). Inclusion of obesity indices was not intended to examine the effects of lifestyle interventions on childhood obesity itself because this has already been examined in another Cochrane Review (Oude Luttikhuis 2009).

 

Search methods for identification of studies

 

Electronic searches

We searched the following electronic databases in May 2013.

  1. Cochrane Central Register of Controlled Trials (CENTRAL) 2013, Issue 4, part of The Cochrane LIbrary.
  2. Ovid MEDLINE (1950 to Week 4 April 2013).
  3. EMBASE (1980 to Week 18 2013).
  4. PsycINFO (1806 to Week 5 April 2013).
  5. CINAHL Plus (1937 to current).
  6. MIT Cognet.
  7. ERIC (1966 to current).
  8. SPORTDiscus.
  9. IBSS - International Bibliography of Social Science (1951 to current).
  10. Conference Proceedings Citation Indexes (1990 to 3 May 2013).
  11. Cochrane Database of Systematic Reviews (CDSR) 2013, Issue 4, part of The Cochrane LIbrary.
  12. Database of Reviews of Effectiveness (DARE) 2013, Issue 2, part of The Cochrane LIbrary.
  13. Database on Obesity and Sedentary Behaviour Studies.
  14. Database of Promoting Health Effectiveness Reviews (DoPHER).
  15. Bibliomap—Database of Health Promotion Research.
  16. Trials Register of Promoting Health Interventions (TRoPHI).
  17. Current Controlled Trials (controlled-trials.com).
  18. WHO International Clinical Trial Registry (who.int/trialsearch).
  19. Networked Digital Library of Theses and Dissertations (ndltd.org).

Search strategies are reported in Appendix 1.

 

Searching other resources

We examined reference lists of systematic reviews and other reviews from The Cochrane Library and the EPPI-Centre, the bibliographies and citations of included studies and relevant guidelines to search for eligible studies.

We handsearched volumes one to seven of The Journal of Human Capital, which is not included in The Cochrane Collaboration handsearching list and is not comprehensively indexed by the databases we searched.

We contacted authors of included studies when outcome data were missing or further details on methodology were needed. Furthermore, authors were asked for new follow-up data that were not available when the study was published.

When necessary, we translated the title and abstract of non–English language studies. If the study appeared to be eligible for inclusion, we obtained the full article and a translation of the article for further assessment. Articles were translated from Chinese (Mandarin), Korean, Japanese, Spanish and German.

 

Data collection and analysis

 

Selection of studies

AM and DHS independently screened titles and abstracts to identify potentially relevant trials and assessed full reports for eligibility. We resolved different opinions about eligibility by discussion; when the review authors did not agree, the other review authors (SJS and JS) arbitrated. We recorded the reasons for excluding trials.

 

Data extraction and management

Two review authors (AM and DHS) independently extracted data using a predefined data extraction form. Cross-checking of extracts was performed to resolve discrepancies. The data extraction form included the following items.

  1. General information: date of data extraction, review author ID, title, published or unpublished, study authors, year of publication, country, contact address, language of publication, source of study.
  2. Eligibility criteria: study design, population, intervention, comparison.
  3. Methods (including risk of bias assessment): study design, randomisation methods, allocation concealment, blinding, handling of missing data, selective data reporting.
  4. Population: method and setting of recruitment; age, gender, ethnicity; inclusion and exclusion criteria; number of participants recruited, included and followed (total and in comparison groups); diagnostic criteria of cognitive function and overweight or obesity; comparability of groups at baseline; co-morbidities.
  5. Intervention: type(s), frequency, mode of delivery, intensity of physical activity, methods and timing of comparison of intervention, setting, intervention and follow-up duration, who delivered intervention, attrition rates, assessment of compliance, details of comparison and control.
  6. Outcome: assessor characteristics, baseline measures, measures immediately after intervention and at follow-up, follow-up time points, validity of measurement tools, definition of outcome (e.g. units, scales), primary outcome, secondary outcome.
  7. Results: qualitative and quantitative data, continuous and dichotomous data, source, missing data, summary statistics for each group.
  8. Analysis: statistical power, methods of analysis, adjustment for confounding.

 

Assessment of risk of bias in included studies

AM and DHS independently assessed the risk of bias in each trial using The Cochrane Collaboration tool for assessing risk of bias (Higgins 2011). Findings were cross-checked and discrepancies resolved through discussion. This included assessment of selection bias (random sequence allocation and allocation concealment), performance bias (blinding of participants and personnel), detection bias (blinding of outcome assessment and incomplete outcome data), reporting bias (selective reporting) and other sources of bias. The review authors judged the risk of bias as 'high risk' of bias, 'low risk' of bias or 'unclear risk' of bias, using the information provided. We intended to resolve disagreements by discussion, and, if necessary, we planned to contact the other review authors (SJS and JS) to ask for advice. No disagreement between AM and DHS occurred.

 

Measures of treatment effect

We calculated or extracted the difference in mean values, that is, mean difference (MD), when continuous data, such as numerical marks, were measured on the same scale. When similar outcomes were measured on different scales, we calculated the standardised mean difference (SMD). When similar outcomes were measured on different scales but were reported as change data by one study and as postintervention data by another, we analysed the treatment effect by calculating the MD (Higgins 2011).

Included studies did not provide dichotomous or ordinal data. However, in  Table 1, we describe how we intend to treat these types of data, if available.

 

Unit of analysis issues

 

Cluster-randomised trials

We scanned all included studies with clustered randomisation of participants for appropriate analysis of clustered data. For studies in which control of clustering was missing or insufficient, and individual participant data were not available, we approximately corrected the intervention effects of cluster-randomised trials by reducing the size of each trial to its 'effective sample size' (Higgins 2011). We planned to calculate the effective sample size in studies with dichotomous data presented as follows: number of participants and number of events divided by the 'design effect', which is [1 + (M-1)* ICC], where M is the average cluster size and ICC is the intracluster correlation coefficient. When outcome measures were continuous, we divided the sample size by the design effect only. A sensitivity analysis was performed to determine the robustness of conclusions from meta-analyses that included cluster-randomised trials. When no ICC was reported, we used the ICC estimate of a similar study. Based on raw data from Ahamed 2007, the ICC of 0.019 was calculated and was used to estimate the effective sample size.

 

Cross-over trials

We considered cross-over trials as eligible for inclusion if participants were randomly assigned into the first period. We planned to include in the analysis only data from the first period, but none of the included studies were cross-over trials (see  Table 1).

 

Multiple interventions per individual

We conducted subgroup analyses for studies that compared the effects of a single intervention (e.g. physical activity alone) versus a control condition separately from studies that compared a combination of any types and numbers of interventions of interest (e.g. physical activity with dietary advice) versus a control condition.

 

Multiple time points

We planned to analyse in a separate meta-analysis data from studies that reported results at more than one time point with comparable data of other studies at similar time points, but none of the included studies provided outcomes at multiple time points (see  Table 1).

 

Dealing with missing data

When possible, we recorded characteristics of, reasons for and quantities of missing data for all included studies. We contacted trial authors to obtain missing data. In our analyses, we ignored data judged to be 'missing at random'. When possible, we imputed missing values in individual participant data using the last observation carried forward (LOCF) method. We performed sensitivity analyses to examine the effects of including imputed data in meta-analyses.

 

Assessment of heterogeneity

We assessed clinical heterogeneity by comparing the similarities of included studies in terms of participants, interventions (type, duration, mode of delivery, setting) and outcomes. By comparing study design and risk of bias, we evaluated methodological heterogeneity. We assessed statistical heterogeneity across studies by visual inspection of the forest plot, and we used the Chi2 test with a significance level of P < 0.1 because of its low power in detecting heterogeneity when studies are low in sample size and numbers of events (Higgins 2011). In addition, we determined the percentage of variability of intervention effect due to statistical heterogeneity among studies by calculating the I2 statistic. Variability greater than 50% may indicate moderate to substantial heterogeneity of intervention effects (Higgins 2011). Furthermore, we assessed the cause of heterogeneity by conducting subgroup and sensitivity analyses, as described below.

 

Assessment of reporting biases

We had planned to assess reporting bias by using funnel plots but were unable to do so because of insufficient numbers of included studies (see  Table 1).

 

Data synthesis

We used Review Manager 5.2 (Review Manager 2011) for data entry and analysis. We combined outcome data from included studies in meta-analyses when the outcome measure addressed the same measurement concept (e.g. school achievement) and used the same measurement scale (e.g. grade point average). We planned to combine dichotomous and continuous data measuring the same outcome as recommended in Chapter 9 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011) but were unable to do so, as all data from included studies were continuous (see  Table 1).

Lifestyle intervention studies have inherent heterogeneity due to intervention implementation and setting, so the true intervention effect is likely to vary between studies. Therefore, we pooled data using the random-effects model and provided effect sizes of studies that were inappropriate to include in a meta-analysis.

 

Subgroup analysis and investigation of heterogeneity

Subgroup analyses are principally intended to investigate sources of heterogeneity within a meta-analysis in relation to factors that potentially impact outcomes. We identified several potentially influential participant and intervention characteristics for subgroup analyses (see  Table 1). However, we performed only one subgroup analysis because of the low number of included studies; this analysis compared studies employing multicomponent versus single component interventions.

 

Sensitivity analysis

We investigated the influence of study characteristics on the robustness of the review results by conducting sensitivity analyses. We removed trials from the analysis when studies:

  1. used different criteria or variations in the thresholds of criteria to define childhood overweight and obesity;
  2. were judged at 'high risk' of bias in the characteristics of random sequence allocation, concealment of allocation, blinding and extent of dropouts;
  3. were cluster RCTs or cross-over trials; and
  4. required imputation of missing data.

 

Results

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms
 

Description of studies

See Characteristics of included studies; Characteristics of excluded studies.

 

Results of the search

The literature search yielded 25,253 records, of which 7567 were duplicates. Sixty-two additional records were found primarily by screening the reference lists of relevant systematic reviews. Most of these additional records targeted the general population rather than the overweight/obesity population only, or were non-randomised controlled trials and therefore were not captured by the search strategy. We screened 17,748 titles and abstracts, and we excluded 17,219 records. Primary or secondary outcomes of this review should not determine whether records are excluded on the basis of title and abstract; therefore we retrieved 529 full-text articles, of which six studies (total sample size = 674) met the inclusion criteria (see Characteristics of included studies). An additional six studies are awaiting classification (see Characteristics of studies awaiting classification), and eight studies are ongoing (see Ongoing studies). A flow chart of the search results is shown in Figure 2.

 FigureFigure 2. Study flow diagram.

 

Included studies

Study design, geographical location and setting

We included two randomised controlled trials (Davis 2011; Staiano 2012) and four cluster-randomised controlled trials (Ahamed 2007; Johnston 2013; Winter 2011; Wirt 2013). Of the six studies, four were conducted in the USA, one was carried out in Canada and one in Germany. Three studies took place in the classroom and/or within the school environment (Ahamed 2007; Johnston 2013; Staiano 2012); one study provided an after-school intervention outside the school setting (Davis 2011), and two studies delivered the intervention both in the classroom and in participants' homes (Winter 2011; Wirt 2013).

Population and sample size

Half of the included studies did not publish data of overweight and/or obese children separately from data of the general population; therefore we contacted the study authors to obtain the data. One study was carried out in preschool children three to five years of age (Winter 2011), four studies conducted the intervention in primary school children six to 13 years of age (Ahamed 2007; Davis 2011; Johnston 2013; Wirt 2013) and another study included adolescents 15 to 18 years of age (Staiano 2012). The numbers of participants randomly assigned ranged from 37 to 321 (total N = 792). The overall proportions of girls were 57% and 53% in Staiano 2012 and Wirt 2013, respectively. Proportions of girls in the intervention group were 54% (Davis 2011), 48% (Ahamed 2007), 38% (Johnston 2013) and 25% (Winter 2011), whereas proportions of girls in the control group were 62% (Davis 2011), 19% (Ahamed 2007), 46% Johnston 2013) and 37% (Winter 2011). Ethnic majorities in the study populations were Black (Davis 2011; Staiano 2012), Hispanic (Johnston 2013; Winter 2011), Asian (Ahamed 2007) and South-East European (Wirt 2013). Attrition rates were 5.2% (Davis 2011), 21.0% (Johnston 2013), 24.3% (Wirt 2013), 27.0% (Staiano 2012), 27.5% (Winter 2011) and 29.1% (Ahamed 2007).

Interventions and comparisons

Four of the included studies involved multicomponent lifestyle interventions (Ahamed 2007; Johnston 2013; Winter 2011; Wirt 2013); the remaining two studies involved single component physical activity interventions. All interventions included engagement in physical activity; however, type, intensity, duration and frequency varied between studies. Types of physical activity ranged from aerobic physical activity group sessions (Ahamed 2007; Davis 2011; Wirt 2013) and general encouragement to increase physical activity throughout the day (Johnston 2013; Winter 2011) to playing an active video game ('exergaming') (Staiano 2012). Multicomponent interventions included, in addition to the physical activity component, a behavioural change intervention in the form of healthy lifestyle or nutrition education (Ahamed 2007; Johnston 2013; Winter 2011; Wirt 2013) and dietary intervention (Ahamed 2007; Johnston 2013). Interventions lasted 10 to 13 weeks (Davis 2011; Staiano 2012), six months (Winter 2011), one school year (Ahamed 2007; Wirt 2013) and two school years (Johnston 2013). The comparison condition for all included studies was 'standard care', referring to usual physical activity and/or usual school curriculum, including physical education lessons. One study applied a waiting list control condition (Wirt 2013).

Outcomes

In all studies, outcomes were measured at baseline and immediately after the intervention period was completed. None of the studies performed further follow-up assessments. See Appendix 2 for a summary of the measurement tools used to assess primary and secondary outcomes.

1. School achievement.

School achievement was assessed for mathematics (Ahamed 2007; Davis 2011; Johnston 2013), vocabulary skills (Winter 2011), reading (Ahamed 2007; Davis 2011; Johnston 2013), English/language arts (Ahamed 2007) and science (Johnston 2013) using the Woodcock-Johnson Tests of Achievement III (Davis 2011), the Canadian Achievement Test (CAT)-3 (Ahamed 2007), the Peabody Picture Vocabulary Test III (Winter 2011) and local achievement assessment criteria (Johnston 2013). Of the four studies that assessed school achievement, two provided overall scores/grade point average (GPA) (Ahamed 2007; Johnston 2013). The remaining studies reported subject-specific scores. Although receptive vocabulary skills measured by the Peabody Picture Vocabulary Test are often used as measures of general intelligence, we classified these as school achievement outcomes because the trial authors intended to assess school readiness.

2. Cognitive function.

Four of the six included studies assessed cognitive function. Most studies measured specific cognitive domains rather than general intelligence. Two studies assessed executive function using the Das-Naglieri-Cognitive Assessment System (CAS) (Davis 2011) and the Delis-Kaplan Executive Function System (Staiano 2012); two further studies assessed attention using the Das-Naglieri-CAS (Davis 2011) and the KiTAP (Wirt 2013). Other cognitive domains included inhibitory control assessed by the KiTAP (Wirt 2013) and successive and simultaneous processing assessed by the Das-Naglieri-CAS (Davis 2011).

3. Future success.

None of the included studies assessed measures of future success.

 

Excluded studies

In total, 498 full-text articles were excluded. For 420 articles, primary and secondary outcomes of interest were not reported in the article. Further reasons for exclusion were non-randomised study design (12 articles), ineligible population (28 articles), ineligible intervention (10 articles) and missing/ineligible control condition (23 articles). Articles were excluded when the age of the population did not fall into the age range of three to 18 years, or when studies did not focus on overweight or obese children. Ineligible interventions were considered to be those that did not aim to prevent or treat childhood overweight or obesity, for example, a behaviour change intervention to reduce teasing or health risk behaviours such as aggression. Lifestyle interventions that were too short in duration (e.g. a one-off session of 20 minutes of physical activity) were not suitable for weight management and thus were not eligible for inclusion. Three articles were excluded because of self reported outcomes, one article reported cognitive function scores related to appetite control rather than school achievement and one study provided an inadequate end-of-intervention outcome measure.

The number of excluded full-text screened studies was too high to list the reason for exclusion for each excluded study in Characteristics of excluded studies; therefore we listed only those lifestyle intervention studies that did not meet all inclusion criteria but:

  1. intended to prevent or treat childhood overweight or obesity and reported measures of school achievement or cognitive function (Delgado-Rico 2012b; Gunnarsdottir 2012b; Hollar 2010; Hutson 2008; Leidy 2013; Milosis 2007; Reed 2012; Robinson 2010; Vanhelst 2012; Verbeken 2013; Vos 2011); and
  2. reported measures of school achievement or cognitive function with a specific focus on overweight/obese children and adolescents without the primary intention to prevent or reduce obesity (Bartholomew 2011; Grieco 2009; Hill 2011; Tomporowski 2008).

 

Risk of bias in included studies

The Characteristics of included studies table provides the reasons for the judgements of risk of bias for each bias item. Figure 3 and Figure 4 illustrate the judgement for each risk of bias item across all included studies and for each included study, respectively.

 FigureFigure 3. Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
 FigureFigure 4. Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

 

Allocation

Random sequence generation. Three studies were judged to be at unclear risk of bias (Ahamed 2007; Staiano 2012; Winter 2011) and three studies were judged to be at low risk of bias for random sequence generation (Davis 2011; Johnston 2013; Wirt 2013).

The difference in gender proportion across experimental groups in Ahamed 2007 may indicate a high risk of bias for randomisation. However, differences in the proportions of overweight girls across groups can be explained by a cluster effect and lack of stratified randomisation by gender. Data used for this review were obtained only from a subgroup of the total study population (i.e. overweight and obese children). The gender distribution between intervention and control schools for the entire study population is fairly equal (intervention group 50.7% girls, control group 47.4% girls). It is unclear why the proportion of overweight girls is substantially lower in the control group than in the intervention group; this could have occurred by chance. Nevertheless, the comparability of baseline groups might be at risk of bias (see Other potential sources of bias).

Allocation concealment. Of the six included studies, the risk of bias for allocation concealment was judged as unclear for three studies (Johnston 2013; Staiano 2012; Winter 2011) and low for three studies (Ahamed 2007; Davis 2011; Wirt 2013).

 

Blinding

Participants and personnel. True blinding of participants and personnel involved in delivering the intervention is not possible in a lifestyle intervention study. However, three studies (Ahamed 2007; Davis 2011; Staiano 2012) blinded participants and personnel to the true purpose of the study and therefore were judged to be at low risk for performance bias. Two studies were judged to be at unclear risk for performance bias (Johnston 2013; Winter 2011). Wirt 2013 was judged to be at high risk for performance bias because the personnel (teachers) were not blinded, although participants were blinded to the true purpose of the study.

Outcome assessment. The risk of bias for blinding of outcome assessment was judged to be unclear for two studies (Johnston 2013; Winter 2011) and low for four studies (Ahamed 2007; Davis 2011; Staiano 2012; Wirt 2013).

 

Incomplete outcome data

Of the six included studies, the risk for attrition bias was judged to be low in three studies (Davis 2011; Johnston 2013; Winter 2011) but high in three studies (Ahamed 2007; Staiano 2012; Wirt 2013) in which no imputation of missing data was performed. The study authors provided the reasons for attrition (see Characteristics of included studies). Attrition rates for studies judged to be at high risk were as follows.

  1. Ahamed 2007: 29.1%, with 16.6% higher attrition in the intervention group than in the control group (intervention arm 26 of 78 children, control arm four of 25 children).
  2. Staiano 2012: 27%, with 16.3% and 13.8% higher attrition in the the two interventions arms than in the control group (competitive intervention condition nine of 19 children, cooperative intervention condition eight of 19 children, control arm three of 19 children).
  3. Wirt 2013: 24.3% (10 of 37 children). No group-specific data were available on different attrition rates at the child level. Instead, cluster-level data refer to the whole study population rather than to overweight and obese children only.

Reasons for higher attrition in intervention groups compared with the control group in Staiano 2012 could be intervention related, such as the reported reason that self consciousness due to obesity was increased by taking part in the intervention or lack of interest. Other reported reasons, such as school transfer or pregnancy, are less likely to be attributable to taking part in the intervention. Similar intervention-related effects might be the reason for higher attrition in the intervention group in Ahamed 2007. However, as this study is a cluster-RCT, reasons for higher attrition in intervention schools than control schools might be associated with the schools themselves rather than with the interventions. Ahamed 2007 reported that proportionately more children from intervention schools moved or were absent on the day of testing compared with children from control schools. Wirt 2013 reported that dropout occurred only at a school or class level, and that attrition was double for classes in the control group (two classes) compared with the intervention group (one class). The reasons for missing data are described in Characteristics of included studies.

 

Selective reporting

The risk for selective reporting was judged to be low in five studies (Ahamed 2007; Davis 2011; Staiano 2012; Winter 2011; Wirt 2013) and unclear in the remaining study (Johnston 2013).

 

Other potential sources of bias

Two additional potential biases were detected.

  1. Comparability of baseline groups might be a potential source of bias in cluster-RCTs (four studies). Two cluster-RCTs were free of this source of bias (Johnston 2013; Winter 2011). Two studies were judged to be at unclear risk of bias (Ahamed 2007; Wirt 2013).
  2. Body weight alone is an unreliable measure of obesity and hence is at risk of measurement bias. One study was judged to be at high risk of measurement bias for measurement of obesity (Staiano 2012). The remaining studies were free of this potential source of bias because obesity status was assessed using established age- and gender-specific BMI cutoffs.

 

Effects of interventions

See:  Summary of findings for the main comparison Lifestyle interventions versus standard care for improving school achievement—Findings after sensitivity analysis;  Summary of findings 2 Lifestyle interventions versus standard care for improving school achievement—Findings before sensitivity analysis

 

Primary outcomes

The limited number of included studies restricts the usefulness of meta-analyses. Therefore, we present the findings on school achievement for each study separately. When possible, we determined the statistical heterogeneity of studies using similar methodology. For studies that did not take cluster-randomisation into account (Ahamed 2007; Winter 2011), we corrected the numbers of participants for cluster-randomisation by calculating the effective sample size (see Unit of analysis issues). No subgroup analysis was performed because of the low number of included studies. For a summary of the effects of lifestyle interventions on primary outcomes, see  Summary of findings for the main comparison and  Summary of findings 2. We have prioritised reporting of the sensitivity analysis when risk of bias and differences in intervention types and duration were suspected to have influenced the findings substantially ( Summary of findings for the main comparison).

 

1. Overall school achievement

Two studies provided pre/postintervention change data on the effects of school-based, multicomponent lifestyle interventions on overall achievement for overweight and obese children in the subjects of mathematics, reading, language (Ahamed 2007 only) and science (Johnston 2013 only).

Johnston 2013 tested the effects of healthy lifestyle education and nutrition interventions on GPA scores in 321 overweight and obese children seven to nine years of age. Findings indicate an MD of 1.78 points (95% confidence interval (CI) 0.8 to 2.76; P < 0.001) on a scale of zero to 100 favouring the intervention group. Ahamed 2007 described the findings of 'Action Schools! BC', an intervention focused on increasing the physical activity and fruit and vegetable intake of children seven to 11 years of age. Intervention effects on average school achievement, measured using the CAT-3 in 64 overweight and obese children, suggested a non-significant beneficial effect in the control group (MD -16.53, 95% CI -86.63 to 53.57; P value = 0.64; scale mean score 500; scale SD 70).

The two studies were combined in a meta-analysis. Although similar in terms of age groups, intervention modes and outcomes, a high level of statistical heterogeneity (I2) was noted. This could be explained by differences in intervention dose. The intervention duration in Johnston 2013 was two years, which is double the dose of the study by Ahamed 2007. Risk of bias assessment suggests a high risk of attrition bias in Ahamed 2007, whereas for Johnston 2013, information for most risk of bias items was not obtainable; therefore risk was assessed as 'unclear'. Because different assessment scales were used, the SMD of change scores in school achievement between intervention and control groups was calculated (SMD 0.19, 95% CI -0.36 to 0.75; P value = 0.5; I2 = 73%) ( Analysis 1.1). The combined results suggest no significant benefit of multicomponent lifestyle interventions for overall school achievement in overweight and obese primary school–aged children.

 

2. Subject-specific achievement

 
2.1 Mathematics achievement

The effects of lifestyle interventions on mathematics achievement were assessed in two studies. One study was a single component study employing an after-school, aerobic physical activity intervention (Davis 2011), and one study was a multicomponent intervention study (Ahamed 2007). These studies differed in the test tool used to assess mathematics achievement; Davis 2011 applied the Woodcock-Johnson Tests of Achievement III, whereas Ahamed 2007 used the Canadian Achievement Test-3.

Individual study data from Davis 2011 show that 40 minutes of vigorous intensity physical activity on five days per week over a period of 13 weeks significantly improved mathematics achievement in overweight and obese children seven to 11 years of age (N = 96). The MD of mathematics scores was 3.00 points (95% CI 0.78 to 5.22; P value = 0.008) relative to the standardised test score, with a mean of 100 and an SD of 15. A statistically significant beneficial effect was also detected in the multicomponent lifestyle intervention of Ahamed 2007. The MD of mathematics scores between the experimental groups of 73 overweight children nine to 11 years of age was 41 points (95% CI 6.5 to 75.50; P value = 0.02) relative to the standardised mean score of 500 (SD 70).

Pooled study data yielded an SMD in achievement scores of 17.94 units (95% CI -18.44 to 54.32; P value = 0.33;  Analysis 1.2). Differences in lifestyle intervention design (single vs multicomponent) and dose (13 weeks vs one school year) are assumed to be the reasons for substantial heterogeneity between studies (I2 = 78%), which potentially resulted in the non-significant beneficial effects of lifestyle interventions on mathematics achievement.

 
2.2 Language achievement

Language achievement included both reading and writing skills of children and adolescents and was assessed by Ahamed 2007. Results from this single study showed no significant effect of a school-based, multicomponent lifestyle intervention, aiming to increase physical activity and fruit and vegetable intake, on language achievement in 73 overweight or obese children (nine to 11 years of age). The MD of language achievement scores between intervention and control groups was 27.97 points (95% CI -5.35 to 61.29; P value = 0.10; scale mean 500, SD 70) ( Analysis 1.3).

 
2.3 Reading achievement

Similar to mathematics achievement, reading achievement was assessed by the two studies, which differed in types of interventions (after-school physical activity vs school-based physical activity and dietary changes) and intervention duration (13 weeks vs one school year), as well as in the tools used to assess reading achievement (Woodcock-Johnson Tests of Achievement III vs Canadian Achievement Test-3). Individual study data from both studies suggested no significant beneficial effect of the interventions on reading achievement (Ahamed 2007; Davis 2011). The MD was 0.00 (95% CI -2.22 to 2.22; P value = 1.00) relative to the standardised test score, with a mean of 100 and an SD of 15 in Davis 2011, and 12.76 units (95% CI -16.74 to 42.25; P value = 0.40; scale mean 500, SD 70) in Ahamed 2007. No statistical heterogeneity was detected after the two studies were combined (SMD 0.07 units, 95% CI -2.14 to 2.28; P value = 0.95; I2 = 0%) ( Analysis 1.4).

 
2.4. Writing achievement

None of the included studies provided data on the effects of lifestyle interventions on writing achievement in overweight or obese children and adolescents.

 
2.5. Vocabulary achievement

Vocabulary achievement was assessed by one study (Winter 2011) using the Peabody Picture Vocabulary Test III. No evidence was found of an effect of lifestyle education combined with encouragement in increasing physical activity on vocabulary skills in overweight and obese preschool children (three to five years of age) regardless of whether missing data were imputed. The proportion of missing data that required imputation was 27.5% of the total sample. This proportion is considered to be high (Fewtrell 2008). Therefore, we reported the results for the study population with postintervention measures separately from the results after imputation of missing postintervention data. The MD for imputed data was 1.19 units (95% CI -4.04 to 6.42; P value = 0.69; N = 80); the MD for 66 participants without missing data was 2.60 units (95% CI -3.04 to 8.24; P value = 0.40) relative to the standardised test score, with a mean of 100 and an SD of 15 ( Analysis 1.5).

 

3. Special education classes

No study provided data on the effects of lifestyle interventions on the need for special education classes or on reduction of time allocated for special education classes.

 

Secondary outcomes

 

1. Cognitive function

Data for evaluating the effects of lifestyle intervention on cognitive function were available from three studies (Davis 2011; Staiano 2012; Wirt 2013). As for the primary outcomes, findings for each study are described by types of outcome measures and, when suitable, results of meta-analyses, which also describe heterogeneity between studies, are presented. The low number of included studies prevented us from conducting meaningful subgroup analyses. All three studies delivered a physical activity intervention, and one of the three studies also included healthy lifestyle education (Wirt 2013). We corrected the number of participants for cluster randomisation for Wirt 2013 and calculated the effective sample size (see Unit of analysis issues).

1.1 Attention

Davis 2011 and Wirt 2013 assessed the effects of lifestyle interventions on attention abilities in overweight and obese children. No significant evidence showed a beneficial effect of 40 minutes of vigorous aerobic physical activity, on five days per week for a total of 13 weeks, on attention scores in 116 children seven to 11 years of age, as measured by the Das-Naglieri-Cognitive Assessment System. The MD was 0.00 units (95% CI -3.05 to 3.05; P value = 1.00) relative to the standardised test score, with a mean of 100 and an SD of 15 (Davis 2011). In contrast, an intervention combining lifestyle education and physical activity lessons in school over one school year indicated a significant beneficial effect of attention scores in the preschool-aged control group (N = 27) (Wirt 2013). The MD was -4.47 units (95% CI -8.55 to -0.39; P value = 0.03; standardised scale mean 50, SD 10). Wirt 2013 used the KiTAP tool to assess attention abilities.

Meta-analysis indicated moderate heterogeneity (I2 = 56%) between the combined studies; this is most likely explained by the different types of interventions. Combined results showed no statistically significant evidence of the effects of lifestyle interventions on attention ability in 143 overweight and obese children six to 11 years of age based on two studies (SMD - 0.25 units, 95% CI -0.92 to 0.41; P value = 0.46) ( Analysis 1.6).

1.2 Executive function

Davis 2011 and Staiano 2012 reported findings on executive function in overweight and obese children and adolescents after participation in a physical activity intervention. Individual study data by Davis 2011 suggest that an after-school vigorous intensity physical activity intervention (40 minutes on five days per week over 13 weeks) improved executive function scores by three points (95% CI 0.09 to 5.91; P value = 0.04; scale mean 100, SD 15; N = 116), as assessed by the planning scale of the Das-Naglieri-Cognitive Assessment System. On the contrary, a school-based exergaming intervention, with a competitive or cooperative condition that took place, on average, once a week for 30 to 60 minutes, was not beneficial in improving the executive function of 52 children 15 to 18 years of age compared with usual school routine (Staiano 2012). The MD for the cooperative exergaming condition was 4.18 (95% CI -9.90 to 18.26; P value = 0.56), and the MD for the competitive condition was 12.99 (95% CI -1.54 to 27.52; P value = 0.08). Executive function was assessed using the Design Fluency and Trail-Making subscales of the Delis-Kaplan Executive Function System (scale mean 10, SD 3).

Despite the difference in children's ages between studies, these studies are similar in methodology and outcome; hence, we performed a meta-analysis, which suggested that physical activity interventions can improve executive function in 170 overweight or obese children and adolescents seven to 18 years of age. The MD was 3.42 units (95% CI 0.62 to 6.22; P value = 0.02; I2 = 0%) ( Analysis 1.7; Figure 5). One study reported postintervention scores (Davis 2011), and the other study reported change scores (Staiano 2012). Therefore, we used the mean difference, rather than the standardised mean difference, to evaluate the effects of physical activity on executive function in overweight and obese children (Higgins 2011).

 FigureFigure 5. Forest plot of comparison: 1 Lifestyle interventions versus standard care, outcome: 1.7 Executive function.

1.3 Inhibitory control

One study assessed the effects of school-based lifestyle education, including physical activity lessons for a period of one year, on inhibitory control in overweight or obese children (Wirt 2013). No significant evidence was found of an intervention effect on inhibitory control in 18 overweight or obese preschool children (six to eight years of age). The MD was 0.26 units (95% CI -1.27 to 1.79; P value = 0.74; standardised scale mean 50, SD 10) ( Analysis 1.8).

1.4 Working memory

Working memory was assessed by the successive processing scale of the Das-Naglieri-Cognitive Assessment System. Results show that 40 minutes of vigorous intensity physical activity on five days per week, over a total of 13 weeks, significantly improved working memory in overweight and obese children (N = 116) seven to 11 years of age (Davis 2011). The MD of working memory scores between intervention and control groups was 3.00 units (95% CI 0.51 to 5.49; P value = 0.02) relative to the standardised test score, with a mean of 100 and an SD of 15 ( Analysis 1.9).

1.5 Simultaneous processing

The simultaneous processing scale of the Das-Naglieri-Cognitive Assessment System tests verbal and non-verbal spatial relations and memory. No significant evidence was found of an effect of the after-school physical activity intervention of Davis 2011 on simultaneous processing ability in 116 overweight or obese children seven to 11 years of age. The MD was 1.00 unit (95% CI -2.19 to 4.19; P value = 0.54) relative to the standardised test score, with a mean of 100 and an SD of 15 ( Analysis 1.10).

 

2. Future success

No study provided data on the effects of lifestyle interventions on future success such as years of schooling, earning or college enrolment for overweight or obese children and adolescents.

 

3. Obesity indices

The effects of lifestyle interventions on body weight status were assessed only for included studies that indicated a significant effect (positive or negative) on at least one of the above outcome measures. Four of six included studies reported a significant change in measures of school achievement and/or cognitive function (Davis 2011; Johnston 2013; Staiano 2012; Wirt 2013). Staiano 2012, however, reported an intervention effect on body weight only, which is not considered a reliable tool for determining overweight and obesity. Therefore only the results of Davis 2011, Johnston 2013 and Wirt 2013 are presented.

 
3.1. Body mass index (BMI) z-score

Two studies provided data on the effects of a physical activity intervention (Davis 2011) and a multicomponent intervention (Johnston 2013) on BMI z-scores. Johnston 2013 provided change scores, and Davis 2011 reported postintervention BMI z-scores. Findings from Davis 2011 suggest a significant beneficial effect on the BMI z-scores of overweight and obese children in the control group. The MD was 0.12 BMI z-scores (95% CI 0.07 to 0.17; P < 0.001) (Davis 2011). Evidence from the multicomponent intervention (school-based lifestyle education and nutritional changes) shows a small but significant beneficial effect on changes in BMI z-scores in 321 overweight and obese children, with an MD of -0.06 BMI z-scores (95% CI -012 to 0.00; P value = 0.04).

Meta-analysis including both studies showed substantial heterogeneity between studies (I2 = 96%), which can be explained by substantial methodological differences in the interventions (type, setting, duration) ( Analysis 1.11).

 
3.2. Body mass index (BMI) standard deviation score (SDS)

A school-based lifestyle education intervention, including physically active lessons, had an effect on BMI SDS that was not statistically significant (Wirt 2013). The MD was 0.34 standard deviations (95% CI -0.01 to 0.69; P value = 0.06; N = 30) ( Analysis 1.12).

 
3.3. Body mass index (BMI) centile

No significant effect of lifestyle interventions on BMI centiles was found in 30 overweight or obese children six to 11 years of age. The MD was 2.26 centiles (95% CI -0.86 to 5.38; P value = 0.16) (Wirt 2013;  Analysis 1.13).

 

Sensitivity analysis

The low number of included studies limits the applicability of subgroup analysis and sensitivity analysis. Nevertheless, sensitivity analyses were performed to consider the impact of cluster-RCTs and/or 'high risk' attrition bias on the intervention effect. Sensitivity analyses show that results on reading achievement, executive function and attention and the overall conclusion were not affected by the inclusion of cluster-RCTs and studies with high attrition. However, results on the effects of lifestyle interventions on overall school achievement and on mathematics achievement became significantly statistically when the cluster-RCT, which was also at 'high risk' of attrition bias, was excluded. Sensitivity analyses suggested a beneficial effect of a school-based, healthy lifestyle education and nutrition intervention and an aerobic physical activity intervention on overall school achievement and on mathematics achievement in overweight and obese primary school children, respectively.

 

Discussion

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms
 

Summary of main results

School achievement. Of the six included studies, four assessed the effects of lifestyle interventions on school achievement in overweight and obese children. Studies used different concepts of school achievement (i.e. overall school achievement or achievement in specific school subjects), which meant that only one or two studies could be included per outcome measure for analysis. No evidence was found of a beneficial effect of multicomponent lifestyle interventions on changes in overall school achievement in overweight and obese children seven to 11 years of age (Ahamed 2007; Johnston 2013). However, when both available studies were considered separately, the study with a lower risk of bias and a longer intervention duration suggested a small but significant benefit of a multicomponent intervention (MD 1.78 points, 95% CI 0.8 to 2.76; P < 0.001; scale range zero to 100; Johnston 2013). Similarly beneficial effects were detected for mathematics achievement. Combined results of available studies did not indicate improvement in mathematics achievement in the intervention group, most likely attributable to the large heterogeneity of the studies in terms of types and duration of interventions. However, after sensitivity analysis, individual study findings on the physical activity only intervention yielded an increase of three points in mathematics scores for overweight and obese children (95% CI 0.78 to 5.22; P value = 0.008; scale mean 100, SD 15) (Davis 2011). No statistically significant evidence was found for improvement in reading achievement, language achievement and vocabulary skills.

Cognitive function. Three studies investigated the effects of lifestyle interventions on five different specific cognitive abilities: executive function, inhibitory control, attention, working memory and simultaneous processing. Results showed significant improvement in executive function and working memory in overweight and obese children and adolescents (Davis 2011; Staiano 2012). The MD for executive function was 3.42 (95% CI 0.62 to 6.22; P value = 0.02) and for working memory 3.00 (95% CI 0.51 to 5.49; P value = 0.02). No significant evidence was found of a beneficial effect of lifestyle interventions on inhibition control (Wirt 2013), attention (Davis 2011; Wirt 2013) or simultaneous processing (Davis 2011) in overweight and obese children.

Future success. No data currently exist on whether lifestyle interventions for overweight or obese children and adolescents influence indices of future success once schooling has been completed.

Obesity indices. We analysed the effects of lifestyle interventions on obesity indices in studies that indicated a statistically significant effect of lifestyle interventions on school achievement or cognitive function. This enabled us to assess whether changes in outcome variables occurred independently of changes in obesity in three studies. One study suggested a small but significant beneficial effect on both average achievement and BMI z-scores (Johnston 2013); this was the largest and longest trial at low risk of bias. Another study reported a beneficial effect on BMI z-scores in the control group (Davis 2011). No evidence was found of a statistically significant benefit of lifestyle interventions for BMI SDSs and BMI centiles (Wirt 2013).

 

Overall completeness and applicability of evidence

Very few studies have investigated the effects of lifestyle interventions on school achievement or cognition in overweight and obese children and adolescents, and reported studies have a range of methodological issues (see Quality of the evidence). During the literature review, we faced several challenges related to the nature of the intervention, the study population and outcomes. A lifestyle intervention is a broad and complex construct. We followed the definition used by clinical guidelines for the prevention and treatment of childhood obesity (see Description of the intervention) and developed the search strategy on this basis. We might have missed studies that applied childhood obesity–related lifestyle interventions that fall outside the definition used. Moreover, our literature search focused on lifestyle intervention studies that intended to prevent or reduce childhood obesity. Studies that employed a lifestyle intervention that is part of paediatric weight management but was not provided to prevent or reduce obesity were likely not to be included in this review. Our population group of interest—overweight and obese children and adolescents—is a very specific, yet substantial and increasing, subgroup of the general population. Many studies did not report results of the overweight or obese subgroup separately from those of normal weight children. For some studies, the data were not obtainable to date. Finally, lifestyle intervention studies in this population do not tend to assess and/or report school achievement, cognitive function or future success as primary or secondary outcomes.

All included studies were conducted in high-income countries. Although some studies targeted low-income children (Staiano 2012; Winter 2011), evidence might not be applicable to low- and middle-income countries. Available evidence for school achievement included children of primary school age (six to 11 years) only. Therefore the effects of lifestyle interventions on school achievement in preschool children and adolescents in secondary/high school need to be determined in future studies. In contrast, evidence for cognitive function included a broad age range—from primary school–aged children to high school students up to 18 years of age. No study reported the effects of lifestyle interventions on future success.

Most studies investigated the effects of multicomponent lifestyle interventions on school achievement and cognitive function comprising a nutrition component (e.g. modification of school meals towards nutrient-dense food), a physical activity component and a healthy lifestyle education component. Two studies delivered a single component physical activity intervention. Evidence is lacking on the effects of behaviour change interventions based on established behaviour change techniques for the treatment of childhood obesity, such as stimulus control and self monitoring (NICE 2013; SIGN 2010). None of the included studies employed a single component intervention on healthy diet or reduced intake of sugar-sweetened beverages. Additionally, none of the included studies attempted to determine specifically the effects of reduced sedentary behaviour on school achievement and cognitive function. However, the healthy lifestyle education component by Wirt 2013 included lessons on reducing media screen time, and Ahamed 2007 and Johnston 2013 delivered physically active classroom lessons. Both lifestyle education on reducing media screen time and physically active lessons might be considered as interventions to decrease sedentary behaviour (time spent sitting). The body of available evidence does not allow us to explore whether a specific component of a lifestyle intervention is more effective than another, or whether the multicomponent intervention proves to be the better approach for improving school achievement and cognitive function in overweight and obese children and adolescents. Because all studies performed postintervention measures immediately after intervention with no further follow-up, no evidence on retention of the effect is available.

Overall, the total number of overweight and obese children included in this review is low (N = 674). This limits the generalisability of study results. Moreover, most included studies targeted the general population (normal weight and overweight or obese children), and this might influence the effects of interventions on school achievement and cognition in the overweight and obese paediatric population. Only two studies restricted participants to overweight or obese children and adolescents (Davis 2011; Staiano 2012). These two studies reported promising effects of physical activity interventions on school and cognitive outcomes, but methodological issues may limit applicability of findings for clinical and public health practice.

Only three studies allowed an exploration of whether changes in academic and cognitive abilities were connected to changes in indices of obesity. This connection is unclear because of conflicting findings and variations in study architecture.

 

Quality of the evidence

We used the GRADEpro software developed by the Grading of Recommendations Assessment, Development and Evaluation (GRADE) Working Group (GRADEpro 2008) to assess and grade the quality of evidence of primary outcomes. We performed a sensitivity analysis by generating two 'Summary of findings' tables; the first excluded studies with high risk of bias ( Summary of findings for the main comparison), and the second included all studies ( Summary of findings 2).

Limitations in study design and implementation were noted for language achievement, and a high risk of attrition bias was detected. We considered this limitation to lower confidence in the estimate of effect; therefore we downgraded the evidence by one level. Risk of attrition bias was not considered as a factor affecting the quality of evidence for overall school achievement, mathematics achievement and reading achievement because studies of higher weight were of low risk for attrition bias. Studies aimed at the general population, not at overweight or obese children explicitly, suggested indirectness of outcomes. This occurred for all primary outcomes. However, we downgraded the quality of evidence by one level only for overall school achievement, language achievement and vocabulary achievement. Mathematics and reading achievements were not downgraded for indirectness because the study of higher weight was not affected by indirectness. Moreover, the small sample size of two included studies might suggest imprecision of evidence (wide confidence intervals) for language and vocabulary achievement. Thus, we downgraded the quality for language and vocabulary achievement by one level. We downgraded the quality of evidence for overall school achievement, mathematics achievement and reading achievement by one level as the result of inconsistency of findings most likely caused by differences between studies in intervention type and duration. Given the low number of included studies (fewer than 10 per meta-analysis), we did not assess publication bias using the funnel plot. Risk of bias assessment indicated a low risk of selective reporting for all studies/outcomes, which we regarded as unlikely to negatively affect the quality of evidence. In summary, the quality of evidence for overall school achievement was low, for mathematics and reading achievement moderate, for vocabulary achievement low and for language achievement very low.

Throughout the review, we have prioritised reporting of sensitivity analyses when risk of bias and differences in intervention type and duration were suspected to have substantially influenced the findings. After sensitivity analyses were conducted, the quality of evidence improved for the outcomes of overall achievement, mathematics achievement and reading achievement ( Summary of findings for the main comparison). The quality of evidence for overall school achievement was assessed to be moderate; evidence for indirectness was downgraded because the intervention was aimed at the general population. We did not downgrade the quality of evidence for both mathematics and reading achievement; thus the quality was high.

 

Potential biases in the review process

We intended to review evidence on the effects of an intervention, which is difficult to define in a specific subgroup of the general population; therefore the following limitations should be considered.

First, although we believe that we identified all relevant studies on the reviewed topic, the high number of additional records not identified through our predefined literature search may indicate limitations of our search strategy. However, most of the additionally screened records (identified from reference lists of systematic reviews) described non-randomised lifestyle interventions and/or interventions without specific focus on overweight or obese children. Hence, those records were not intended to be identified by our search strategy, because the studies deviated from the study design and population criteria. On the other hand, because of this, we might have missed relevant studies that included the general population, and separate outcomes for overweight or obese children and adolescents might be obtainable. Of the 62 additional records, only one met the inclusion criteria. Additionally, we might have missed relevant outcomes of at least one study (dissertation) because we could not find contact details of the study author.

Second, given that only a very small number of studies per outcome (one or two studies) with mainly low sample sizes were available, the strength of evidence on the effects of lifestyle interventions for improving school achievement and/or cognitive function in overweight and obese children and youth is limited. Information on whether the studies were adequately powered was insufficient. This was due in part to the fact that data on the overweight and obese subpopulation were provided, and studies were potentially powered for the total study sample. Therefore, both significantly beneficial effects of lifestyle interventions and evidence of no effect need to be considered cautiously.

Third, the absence of an effect might also be attributable to poor adherence to the experimental condition, particularly when the intervention was applied in participants' homes (e.g. physical activity homework tasks). Assessment of participants' compliance with the lifestyle intervention was often poorly reported. We observed a similar bias for assessment of adherence to the control condition. Most studies did not attempt to evaluate and/or report whether the control group maintained its standard care during the trial period. For example, changes in school policy concerning healthy lifestyle factors such as improved school meals or physical activity opportunities during recess could potentially bias the intervention effects of experimental trials. The same may account for engagement in lifestyle changes at the family or child level.

Fourth, most studies linking lifestyle interventions to school achievement and cognitive function in overweight and obese children and youth did not address co-morbidities when selecting the study population. Several co-morbidities are associated with childhood obesity and/or school and cognitive outcomes, including asthma, hypertension, type 2 diabetes and attention-deficit hyperactivity disorder (ADHD). For example, lifestyle interventions for prevention and treatment of obesity (i.e. nutrition, physical education, and health education) also had a significantly beneficial effect on school achievement in children with asthma (Murray 2007). The actual treatment effect of lifestyle interventions in overweight children with co-morbidities may be underestimated or overestimated. On the other hand, Davis 2011 stated that inclusion of overweight children with ADHD did not change the findings on treatment effects.

Fifth, studies used a wide range of school achievement and cognitive function test tools. Although there tend to be correlations between cognitive function tests in particular (because of the general cognitive factor g), different cognitive tests vary in their specificity for different cognitive domains. Moreover, successive testing before and after the intervention is likely to improve participant scores through repeated measures and regression to the mean. Thus, an improvement may not be due to the intervention, although the use of a control group allows some control for this. On the other hand, small participant numbers limit the ability to minimise bias.

 

Agreements and disagreements with other studies or reviews

To our knowledge, no studies have been conducted other than those reviewed and no other (systematic) literature reviews have been performed on this specific topic. However, systematic reviews are available on the effects of physical activity, diet and general school health interventions on school and cognitive achievements in the general population. Although these systematic reviews may include some overweight and obese children, they lack a separately analysed overweight and obese paediatric subgroup; thus they are difficult to compare with this systematic review.

Findings from meta-analyses on physical activity interventions for school achievement and/or cognitive function in the general child and youth population are in agreement with the results of this systematic review, which focused on effects on overweight or obese children only—that is, that physical activity interventions improved school and cognitive outcomes. Sibley 2003 stated that the overall estimated effect size from 16 true experimental studies was 0.24 units (SD 0.24; P < 0.05). A meta-analysis of 39 experimental and quasi-experimental studies by Fedewa 2011 revealed an overall effect size of 0.35 units (standard error (SE) 0.04, 95% CI 0.27 to 0.43; random-effects model). The systematic review on the effects of breakfast consumption and healthy diets on educational achievement by Ells 2008 confirmed the findings of this review in the sense that review authors reported lack of high-quality studies and lack of convincing evidence. Similar results were obtained by Murray 2007, who systematically reviewed the literature on effects of co-ordinated school health programmes, which included, for example, nutrition service, physical education and health education, on school achievement.

Besides the focus on the general child and youth population, these systematic reviews differ from this review in their methodological quality. A thorough assessment of the quality and risk of bias of included RCTs was missing in most of the above studies, and a less rigorous literature search was performed in some of the systematic reviews (e.g. search of selected electronic databases only).

 

Authors' conclusions

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms

 

Implications for practice

Currently, too few data are available to influence practice. However, evidence on the effects of lifestyle interventions does indicate a significant, albeit small, improvement in overall school achievement, mathematics achievement, executive function and working memory in overweight or obese children living in high-income countries. The magnitude of improvement could have practical significance given, for example, that a mean difference of three points represents one third of the change in score required to change from 'low average' to 'average' on a zero to 200 scale of mathematics achievement on the Woodcock-Johnson Tests of Achivement III. An overweight or obese child in the upper range of 'low-average' achievement might benefit from a lifestyle intervention moving into the 'average' achievement category. Therefore, and in addition to previous studies, which have shown beneficial effects for children in general, lifestyle interventions implemented in the school setting, or as after-school programmes, may have the potential to benefit school achievement and associated specific cognitive abilities in overweight and obese children and adolescents. Although these benefits are small, the high prevalence of obesity among children means that the gains could have an impact.

Most included studies took place as part of the curriculum or were implemented in a comprehensive whole-school approach, indicating that similar interventions are feasible to introduce into school practice. Health policy makers may wish to consider these potential additional benefits when promoting physical activity and healthy eating (i.e. body weight–related behaviours) in schools.

Evidence on the effects of lifestyle interventions on school achievement and cognitive function in overweight and obese children conducted in clinical and community settings is missing, and so no implications for clinical practice and community interventions can be drawn.

 
Implications for research

Overall, additional well-designed randomised controlled lifestyle intervention trials in overweight and obese children three to 18 years of age are needed to assess school achievement and/or cognitive function, particularly in low- and middle-income countries, where the prevalence of childhood obesity is rising (WHO 2012). Future childhood obesity treatment trials in both clinical and school settings could consider including school achievement and cognitive outcomes. Studies conducted in the general paediatric population could report school achievement–related outcomes separately for the overweight subgroup. Evidence on the effects of dietary interventions, behaviour change techniques and reduced sedentary behaviour is needed. Low cognitive abilities may be associated with behaviours that cause obesity (reverse causation); therefore identifying which components of lifestyle interventions benefit specific cognitive domains could optimise the physical and cognitive outcomes of obesity treatment programmes. Longer-term follow-up trials are needed to determine whether improvements in school achievement and cognitive function are sustainable over time and thus affect future success. Given that engagement in lifestyle interventions and school achievement and cognitive function vary between gender and ethnicity (Demack 2000), it is important that future trials consider these factors. High rates of loss to follow-up assessment are a common problem in lifestyle interventions, particularly those involving overweight and obese children and adolescents. To reduce the risk of attrition bias, researchers might wish to consider methods to impute missing outcome data in their analysis and to report characteristics of and reasons for missing data. In addition, availability of larger studies might permit investigations of whether a dose-response relationship exists between lifestyle interventions and improvement in school achievement and cognitive function in overweight children and adolescents.

 

Acknowledgements

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms

We would like to thank Laura MacDonald, Professor Geraldine Macdonald and the other members of the editorial team of the Cochrane Developmental, Psychosocial and Learning Problems Group for their guidance and comments. We are grateful for the assistance of Margaret Anderson in developing the search strategy and conducting the literature search. We highly appreciate the efforts of authors of all included studies in providing additional and unpublished data.

 

Data and analyses

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms
Download statistical data

 
Comparison 1. Lifestyle interventions versus standard care

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Overall school achievement2385Std. Mean Difference (IV, Random, 95% CI)0.19 [-0.36, 0.75]

 2 Mathematics achievement2160Std. Mean Difference (Random, 95% CI)17.94 [-18.44, 54.32]

 3 Language achievement164Mean Difference (Random, 95% CI)27.97 [-5.35, 61.29]

 4 Reading achievement2160Std. Mean Difference (Random, 95% CI)0.07 [-2.14, 2.28]

 5 Vocabulary achievement1Mean Difference (IV, Random, 95% CI)Subtotals only

 6 Attention2143Std. Mean Difference (IV, Random, 95% CI)-0.25 [-0.92, 0.41]

 7 Executive function2170Mean Difference (IV, Random, 95% CI)3.42 [0.62, 6.22]

 8 Inhibitory control118Mean Difference (IV, Random, 95% CI)0.26 [-1.27, 1.79]

 9 Working memory1116Mean Difference (IV, Random, 95% CI)3.0 [0.51, 5.49]

 10 Simultaneous processing1116Mean Difference (IV, Random, 95% CI)1.0 [-2.19, 4.19]

 11 BMI z-score2437Mean Difference (IV, Random, 95% CI)0.03 [-0.15, 0.21]

 12 BMI SD-score130Mean Difference (IV, Random, 95% CI)0.34 [-0.01, 0.69]

 13 BMI centile130Mean Difference (IV, Random, 95% CI)2.26 [-0.86, 5.38]

 

Appendices

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms
 

Appendix 1. Search strategies

Cochrane Central Database of Controlled Trials (CENTRAL)

2012 Issue 2 searched on 2 March 2012 [2145 records]

2013 Issue 4 searched on 8 May 2013. Limited to publcation year = 2012 to 2013 [98 records]

#1           MeSH descriptor Overweight explode all trees

#2           MeSH descriptor Body Weight, this term only

#3           (obes* or overweight or over-weight)

#4           MeSH descriptor Body Weight Changes explode all trees

#5           (weight near/2 (loss or lost or losing or reduc*))

#6           (weight near/2 (gain* or increas*))

#7           MeSH descriptor Body Fat Distribution explode all trees

#8           MeSH descriptor Body Mass Index explode all trees

#9           MeSH descriptor Skinfold Thickness explode all trees

#10         MeSH descriptor Waist-Hip Ratio explode all trees

#11         ("body weigh*" or bodyweigh* or "body mass*" or bodymass or "body fat*" or bodyfat*)

#12         MeSH descriptor Overnutrition, this term only

#13         (overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or over-nutrit*)

#14         (#1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9 OR #10 OR #11 OR #12 OR #13)

#15         MeSH descriptor Child explode all trees

#16         MeSH descriptor Adolescent, this term only

#17         (child* or schoolchild* or preschool* or pre-school* or schoolage* or school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen* or adolescen* or youth* or "young people" or "young person*" or pediatr* or paediatr*)

#18         (#15 OR #16 OR #17)

#19         MeSH descriptor Exercise, this term only

#20         MeSH descriptor Exercise Therapy, this term only

#21         MeSH descriptor Physical Exertion, this term only

#22         MeSH descriptor Motor Activity, this term only

#23         MeSH descriptor Sports, this term only

#24         (sport*)

#25         MeSH descriptor Physical Education and Training explode all trees

#26         (physical near/3 (activit* or education* or exertion* or training))

#27         (exercise*)

#28         MeSH descriptor Diet Therapy explode all trees

#29         ((diet or dieting) near/5 (health* or weight*))

#30         (calorie near/3 (control or reduc* or restriction))

#31         "food choice*"

#32         ("fat camp*" or "weight loss camp*")

#33         "nutrition education"

#34         MeSH descriptor Nutrition Therapy, this term only

#35         MeSH descriptor Behavior Therapy, this term only

#36         MeSH descriptor Cognitive Therapy, this term only

#37         MeSH descriptor Psychotherapy, this term only

#38         (behavio?r* near/3 (therap* or technique* or modif* or intervention*))

#39         (cognit* near/3 (therap* or technique* or modif* or intervention*))

#40         CBT

#41         (psychotherap* or psycho-therap*)

#42         MeSH descriptor Family Therapy, this term only

#43         (family near/3 (therap* or intervention*))

#44         family-based

#45         MeSH descriptor Sedentary Lifestyle, this term only

#46         (sedentary near/3 (lifestyle or behavio?r*))

#47         MeSH descriptor Video Games, this term only

#48         MeSH descriptor Television, this term only

#49         (television or tv)

#50         "screen time"

#51         (psycho-social or psychosocial)

#52         MeSH descriptor Health Promotion explode all trees

#53         MeSH descriptor Health Education, this term only

#54         (health* near/3 (promot* or educat* or lifestyle))

#55         MeSH descriptor Life Style, this term only

#56         (lifestyle* or life-style*)

#57         ((video or computer) next game*)

#58         (#19 OR #20 OR #21 OR #22 OR #23 OR #24 OR #25 OR #26 OR #27 OR #28 OR #29 OR #30 OR #31 OR #32 OR #33 OR #34 OR #35 OR #36 OR #37 OR #38 OR #39 OR #40 OR #41 OR #42 OR #43 OR #44 OR #45 OR #46 OR #47 OR #48 OR #49 OR #50 OR #51 OR #52 OR #53 OR #54 OR #55 OR #56 OR #57)

#59         (#14 AND #18 AND #58)

 

Ovid MEDLINE

1950 to 17 February 2012, searched 22 February 2012 [2145 records]

1946 to Week 4 April 2013, searched 7 May 2013. Limited to ED=20120217-20130507 [1009 records]

1     exp Overweight/

2     Body Weight/

3     (obes$ or overweight or over-weight).tw.

4     exp Body Weight Changes/

5     (weight adj2 (loss or lost or losing or reduc$)).tw.

6     (weight adj2 (gain$ or increas$)).tw.

7     exp body fat distribution/ or body mass index/ or skinfold thickness/ or waist-hip ratio/

8     (body weigh$ or bodyweigh$ or body mass$ or bodymass or body fat$ or bodyfat$).tw.

9     Overnutrition/

10     (overeat$ or over-eat$ or overnourish$ or over-nourish$ or overnutrit$ or over-nutrit$).tw.

11     or/1-10

12     exp Child/

13     Adolescent/

14     (child$ or schoolchild$ or preschool$ or pre-school$ or schoolage$ or school-age$ or schoolboy$ or schoolgirl$ or boy$ or girl$ or preteen$ or teen$ or adolescen$ or youth$ or young people or young person$ or pediatr$ or paediatr$).tw. (1087380)

15     12 or 13 or 14

16     Exercise/ or Exercise Therapy/

17     Physical Exertion/

18     Motor Activity/

19     Sports/

20     sport$.tw.

21     exp "Physical Education and Training"/

22     (physical adj3 (activit$ or education$ or exertion$ or training)).tw.

23     exercise$.tw.

24     exp diet therapy/

25     ((diet or dieting) adj5 (health$ or weight$)).tw.

26     (calorie adj3 (control or reduc$ or restriction)).tw.

27     food choice$.tw.

28     (fat camp$ or weight loss camp$).tw.

29     nutrition education.tw.

30     Nutrition Therapy/

31     behavior therapy/

32     Cognitive Therapy/

33     psychotherapy/

34     (behavio?r$ adj3 (therap$ or technique$ or modif$ or intervention$)).tw.

35     (cognit$ adj3 (therap$ or technique$ or modif$ or intervention$)).tw.

36     CBT.tw.

37     (psychotherap$ or psycho-therap$).tw.

38     family therapy/

39     (family adj3 (therap$ or intervention$)).tw.

40     family-based.tw.

41     sedentary lifestyle/

42     (sedentary adj3 (lifestyle or behavio?r$)).tw.

43     video games/

44     television/

45     (television or tv).tw.

46     "screen time".tw.

47     (psycho-social or psychosocial).tw.

48     exp Health Promotion/

49     Health Education/

50     (health$ adj3 (promot$ or educat$ or lifestyle)).tw.

51     lifestyle/

52     (lifestyle$ or life-style$).tw.

53     ((video or computer) adj game$).tw.

54     or/16-53

55     11 and 15 and 54

56     randomized controlled trial.pt.

57     controlled clinical trial.pt.

58     randomi#ed.ab.

59     placebo$.ab.

60     drug therapy.fs.

61     randomly.ab.

62     trial.ab.

63     groups.ab.

64     or/56-63

65     exp animals/ not humans.sh.

66     64 not 65

67     55 and 66

 

EMBASE (Ovid)

1980 to Week 7 2012, searched 22 February 2012 [3887 records]

1980 to Week 18 2013, searched 7 May 2013. Limited to EM=201209-21318 [860 records]

1     exp Overweight/

2     Body Weight/

3     (obes$ or overweight or over-weight).tw.

4     exp Body Weight Changes/

5     (weight adj2 (loss or lost or losing or reduc$)).tw.

6     (weight adj2 (gain$ or increas$)).tw.

7     exp body fat distribution/ or body mass index/ or skinfold thickness/ or waist-hip ratio/

8     (body weigh$ or bodyweigh$ or body mass$ or bodymass or body fat$ or bodyfat$).tw.

9     Overnutrition/

10     (overeat$ or over-eat$ or overnourish$ or over-nourish$ or overnutrit$ or over-nutrit$).tw.

11     or/1-10

12     exp Child/

13     Adolescent/

14     (child$ or schoolchild$ or preschool$ or pre-school$ or schoolage$ or school-age$ or schoolboy$ or schoolgirl$ or boy$ or girl$ or preteen$ or teen$ or adolescen$ or youth$ or young people or young person$ or pediatr$ or paediatr$).tw.

15     12 or 13 or 14

16     Exercise/ or Exercise Therapy/

17     Physical Exertion/

18     Motor Activity/

19     Sports/

20     sport$.tw.

21     exp "Physical Education and Training"/

22     (physical adj3 (activit$ or education$ or exertion$ or training)).tw.

23     exercise$.tw.

24     exp diet therapy/

25     ((diet or dieting) adj5 (health$ or weight$)).tw.

26     (calorie adj3 (control or reduc$ or restriction)).tw.

27     food choice$.tw.

28     (fat camp$ or weight loss camp$).tw.

29     nutrition education.tw.

30     Nutrition Therapy/

31     behavior therapy/

32     Cognitive Therapy/

33     psychotherapy/

34     (behavio?r$ adj3 (therap$ or technique$ or modif$ or intervention$)).tw.

35     (cognit$ adj3 (therap$ or technique$ or modif$ or intervention$)).tw.

36     CBT.tw.

37     (psychotherap$ or psycho-therap$).tw.

8     family therapy/

39     (family adj3 (therap$ or intervention$)).tw.

40     family-based.tw.

41     sedentary lifestyle/ (1338)

42     (sedentary adj3 (lifestyle or behavio?r$)).tw.

43     video games/

44     television/

45     (television or tv).tw.

46     "screen time".tw.

47     (psycho-social or psychosocial).tw.

48     exp Health Promotion/

49     Health Education/

50     (health$ adj3 (promot$ or educat$ or lifestyle)).tw.

51     lifestyle/

52     (lifestyle$ or life-style$).tw.

53     ((video or computer) adj game$).tw.

54     or/16-53

55     11 and 15 and 54

56     random$.tw.

57     factorial$.tw.

58     crossover$.tw.

59     cross over$.tw.

60     cross-over$.tw.

61     placebo$.tw.

62     (doubl$ adj blind$).tw.

63     (singl$ adj blind$).tw.

64     assign$.tw.

65     allocat$.tw.

66     volunteer$.tw.

67     Crossover Procedure/

68     double-blind procedure.tw.

69     Randomized Controlled Trial/

70     Single Blind Procedure/

71     or/56-70

72     55 and 71

 

PsycINFO (Ovid)

1806 to Week 2 February 2012, searched 22 February 2012 [1460 records]

1806 to Week 4 April 2013, searched 7 May 2013, limited to UP=20120218-20130507 [311 records]

1     exp Overweight/

2     Body Weight/

3     (obes$ or overweight or over-weight).tw.

4     (weight adj2 (loss or lost or losing or reduc$)).tw.

5     (weight adj2 (gain$ or increas$)).tw.

6     exp body fat distribution/ or body mass index/ or skinfold thickness/ or waist-hip ratio/

7     (body weigh$ or bodyweigh$ or body mass$ or bodymass or body fat$ or bodyfat$).tw.

8     (overeat$ or over-eat$ or overnourish$ or over-nourish$ or overnutrit$ or over-nutrit$).tw.

9     (child$ or schoolchild$ or preschool$ or pre-school$ or schoolage$ or school-age$ or schoolboy$ or schoolgirl$ or boy$ or girl$ or preteen$ or teen$ or adolescen$ or youth$ or young people or young person$ or pediatr$ or paediatr$).tw.

10     Exercise/ or Exercise Therapy/

11     Physical Activity/

12     Sports/

13     sport$.tw.

14     exp Physical Education/

15     (physical adj3 (activit$ or education$ or exertion$ or training)).tw.

16     exercise$.tw.

17     ((diet or dieting) adj5 (health$ or weight$)).tw.

18     (calorie adj3 (control or reduc$ or restriction)).tw.

19     food choice$.tw.

20     (fat camp$ or weight loss camp$).tw.

21     nutrition education.tw.

22     behavior therapy/

23     Cognitive Therapy/

24     psychotherapy/

25     (behavio?r$ adj3 (therap$ or technique$ or modif$ or intervention$)).tw.

26     (cognit$ adj3 (therap$ or technique$ or modif$ or intervention$)).tw.

27     CBT.tw.

28     (psychotherap$ or psycho-therap$).tw.

29     family therapy/

30     (family adj3 (therap$ or intervention$)).tw.

31     family-based.tw.

32     sedentary lifestyle/

33     (sedentary adj3 (lifestyle or behavio?r$)).tw.

34     video games/

35     television/

36     (television or tv).tw.

37     "screen time".tw.

38     (psycho-social or psychosocial).tw.

39     exp Health Promotion/

40     Health Education/

41     (health$ adj3 (promot$ or educat$ or lifestyle)).tw.

42     lifestyle/

43     (lifestyle$ or life-style$).tw.

44     ((video or computer) adj game$).tw.

45     or/1-8

46     or/10-44

47     9 and 45 and 46

48     Treatment Effectiveness Evaluation/

49     exp Treatment Outcomes/

50     Psychotherapeutic Outcomes/

51     PLACEBO/

52     exp Followup Studies/

53     placebo$.tw.

54     random$.tw.

55     comparative stud$.tw.

56     randomi#ed controlled trial$.tw.

57     (clinical adj3 trial$).tw.

58     (research adj3 design).tw.

59     (evaluat$ adj3 stud$).tw.

60     (prospectiv$ adj3 stud$).tw.

61     ((singl$ or doubl$ or trebl$ or tripl$) adj3 (blind$ or mask$)).tw.

62     control$.tw.

63     62 or 54 or 52 or 60 or 59 or 55 or 48 or 53 or 49 or 61 or 57 or 51 or 50 or 58 or 56

64     47 and 63

 

CINAHL Plus (EBSCO host)

1937 to current, searched 22 February 2012 [1933 records]

1937 to current, searched 7 May 2013, limited to EM=20120222- [484 records]

S47  (S44 or S45) and (S43 and S46)

S46  S44 or S45

S45  (MH "Randomized Controlled Trials")

S44  ((random* or blind* or allocat* or assign* or trial* or placebo* or crossover*

or cross-over*))

S43  S9 and S10 and S42

S42  (S11 or S12 or S13 or S14 or S15 or S16 or S17 or S18 or S19 or S20 or S21 or

S22 or S23 or S24 or S25 or S26 or S27 or S28 or S29 or S30 or S31 or S32 or S33

or S34 or S35 or S36 or S37 or S38 or S39 or S40 or S41)

S41  (((video or computer) N1 game*))

S40  ((lifestyle* or life-style*))

S39  ((health* N3 (promot* or educat* or lifestyle)))

S38  ((psycho-social or psychosocial))

S37 ("screen time")

S36  ((television or tv))

S35 ((sedentary N3 (lifestyle or behavio?r*)))

S34  (family-based)

S33 ((family N3 (therap* or intervention*)))

S32 ((psychotherap* or psycho-therap*))

S31 CBT

S30 ((cognit* N3 (therap* or technique* or modif* or intervention*)))

S29 ((behavio#r* N3 (therap* or technique* or modif* or intervention*)))

S28 ("nutrition education")

S27 (("fat camp*" or "weight loss camp*"))

S26 ("food choice*")

S25 ((calorie N3 (control or reduc* or restriction)))

S24  (((diet or dieting) N5 (health* or weight*)))

S23 (exercise*)

S22 ((physical N3 (activit* or education* or exertion* or training)))

S21 (sport*)

S20 (MH "Health Education")

S19 (MH "Health Promotion")

S18 (MH "Life Style")

S17 (MH "Television")

S16 (MH "Video Games")

S15 (MH "Family Therapy")

S14 (MH "Cognitive Therapy")

S13 (MH "Diet Therapy") OR (MH "Behavior Therapy")

S12 (MH "Sports")

S11 (MH "Exercise") OR (MH "Physical Fitness")

S10 ((child* or schoolchild* or preschool* or pre-school* or schoolage* or

school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen*

or adolescen* or youth* or young people or young person* or pediatr* or

paediatr*))

S9  S1 or S2 or S3 or S4 or S5 or S6 or S7 or S8

S8  ((overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or

over-nutrit*))

S7  (("body weigh*" or bodyweigh* or body mass* or bodymass or "body fat*" or

bodyfat*))

S6  ((weight N2 (gain* or increas*)))

S5  ((weight N2 (loss or lost or losing or reduc*)))

S4 (MH "Hyperphagia")

S3  (MH "Weight Loss")

S2 (MH "Obesity")

S1 ((obes* or overweight or over-weight))

 

IBSS (International Bibliography of Social Studies) (Proquest)

1951 to current, searched 22 February 2012 [459 records]

1951 to current, searched 8 May 2013, limited to publication year 2012 to 2013 [113 records]

    S1  ((obes* or overweight or over-weight))

    S2 ((weight near/2 (loss or lost or losing or reduc*)))

    S3 ((weight near/2 (gain* or increas*)))

    S4 (("body weigh*" or bodyweigh* or body mass* or bodymass or "body fat*" or bodyfat*))

    S5 ((overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or over-nutrit*))

    S6 s1 or s2 or s3 or s4 or s5

    S7 ((child* or schoolchild* or preschool* or pre-school* or schoolage* or school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen* or adolescen* or youth* or young people or young person* or pediatr* or paediatr*))

    S8 (sport*)

    S9 ((physical near/3 (activit* or education* or exertion* or training)))

    S10 (exercise*)

    S11 (((diet or dieting) near/5 (health* or weight*)))

    S12 ((calorie near/3 (control or reduc* or restriction)))

    S13 ("food choice*")

    S14 (("fat camp*" or "weight loss camp*"))

    S15 ("nutrition education")

    S16 ((behavio?r* near/3 (therap* or technique* or modif* or intervention*)))

    S17 ((cognit* near/3 (therap* or technique* or modif* or intervention*)))

    S18 (CBT)

    S19 ((psychotherap* or psycho-therap*))

    S20 ((family near/3 (therap* or intervention*)))

    S21 (family-based)

    S22 ((sedentary near/3 (lifestyle or behavio?r*)))

    S23 ((television or tv))

    S24 ("screen time")

    S25 ((psycho-social or psychosocial))

    S26 ((health* near/3 (promot* or educat* or lifestyle)))

    S27 ((lifestyle* or life-style*))

    S28 (((video or computer) near/1 game*))

    S29 s8 or s9 or s10 or s11 or s12 or s13 or s14 or s15 or s16 or s17 or s18 or s19 or s20

    S30 s21 or s22 or s23 or s24 or s25 or s26 or s27 or s28

    S31 s29 or s30

    S32 s6 and s7 and s31

 

ERIC (Proquest)

1966 to current searched 22 February 2012 [1363 records]
1966 to current searched 8 May 2013, limited to publication year 2012 to 2013 [205 records]

S1 ((obes* or overweight or over-weight))

S2 ((weight near/2 (loss or lost or losing or reduc*)))

S3 ((weight near/2 (gain* or increas*)))

S4 (("body weigh*" or bodyweigh* or body mass* or bodymass or "body fat*" or bodyfat*))

S5 ((overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or over-nutrit*))

S6 s1 or s2 or s3 or s4 or s5

S7 ((child* or schoolchild* or preschool* or pre-school* or schoolage* or school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen* or adolescen* or youth* or young people or young person* or pediatr* or paediatr*))

S8 (sport*)

S9 ((physical near/3 (activit* or education* or exertion* or training)))

S10 (exercise*)

S11 (((diet or dieting) near/5 (health* or weight*)))

S12 ((calorie near/3 (control or reduc* or restriction)))

S13 ("food choice*")

S14 (("fat camp*" or "weight loss camp*"))

S15 ("nutrition education")

S16 ((behavio?r* near/3 (therap* or technique* or modif* or intervention*)))

S17 ((cognit* near/3 (therap* or technique* or modif* or intervention*)))

S18 (CBT)

S19 ((psychotherap* or psycho-therap*))

S20 ((family near/3 (therap* or intervention*)))

S21 (family-based)

S22 ((sedentary near/3 (lifestyle or behavio?r*)))

S23 ((television or tv))

S24 ("screen time")

S25 ((psycho-social or psychosocial))

S26 ((health* near/3 (promot* or educat* or lifestyle)))

S27 ((lifestyle* or life-style*))

S28 (((video or computer) near/1 game*))

S29 s8 or s9 or s10 or s11 or s12 or s13 or s14 or s15 or s16 or s17 or s18 or s19 or s20

S30 s21 or s22 or s23 or s24 or s25 or s26 or s27 or s28

S31 s29 or s30

S32 s6 and s7 and s31

Conference Proceeding Citation IndexScience and Conference Proceeding Citation IndexSocial Sciences & Humanities (ISI Web of Knowledge)

1990 to 17 February 2012, searched 22 February 2012 [871 records]
1990 to 3 May 2013, searched 8 May 2013 [12 records]

#32 #31 AND #30

#31 Topic=((random* or blind* or allocat* or assign* or trial* or placebo* or crossover* or cross-over*))

#30 #29 AND #7

#29 #28 OR #27 OR #26 OR #25 OR #24 OR #23 OR #22 OR #21 OR #20 OR #19 OR #18 OR #17 OR #16 OR #15 OR #14 OR #13 OR #12 OR #11 OR #10 OR #9 OR #8

#28 Topic=(((video or computer) near/1 game*))

#27 Topic=((lifestyle* or life-style*))

#26 Topic=((health* near/3 (promot* or educat* or lifestyle)))

#25 Topic=((psycho-social or psychosocial))

#24 Topic=("screen time")

#23 Topic=((television or tv))

#22 Topic=((sedentary near/3 (lifestyle or behavio?r*)))

#21 Topic=(family-based)

#20 Topic=((family near/3 (therap* or intervention*)))

#19 Topic=((psychotherap* or psycho-therap*))

#18 Topic=(CBT)

#17 Topic=((cognit* near/3 (therap* or technique* or modif* or intervention*)))  

#16 Topic=((behavio?r* near/3 (therap* or technique* or modif* or intervention*)))

#15 Topic=("nutrition education")

#14 Topic=(("fat camp*" or "weight loss camp*"))

#13 Topic=("food choice*")

#12 Topic=((calorie near/3 (control or reduc* or restriction)))

#11 Topic=(((diet or dieting) near/5 (health* or weight*)))

#10 Topic=(exercise*)

#9 Topic=((physical near/3 (activit* or education* or exertion* or training)))

#8 Topic=(sport*)

#7 Topic=((child* or schoolchild* or preschool* or pre-school* or schoolage* or school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen* or adolescen* or youth* or young people or young person* or pediatr* or paediatr*))

#6 #5 OR #4 OR #3 OR #2 OR #1

#5 Topic=((overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or over-nutrit*))

#4 Topic=(("body weigh*" or bodyweigh* or body mass* or bodymass or "body fat*" or bodyfat*))

#3 Topic=((weight near/2 (gain* or increas*)))

#2 Topic=((weight near/2 (loss or lost or losing or reduc*)))

#1 Topic=((obes* or overweight or over-weight))

Cochrane Database of Systematic Reviews

2012 (Issue 12), searched 15 January 2012 [ 22 records]
2013 (Issue 4), searched 8 May 2013, limited to publication year 2012 to 2013 [11 records]

#1MeSH descriptor: [Overweight] explode all trees
#2MeSH descriptor: [Body Weight] this term only
#3(obese or obesity or overweight or over-weight):ti,ab
#4MeSH descriptor: [Body Weight Changes] explode all trees
#5(weight near/2 (loss or lost or losing or reduc*)):ti,ab
#6(weight near/2 (gain* or increas*)):ti,ab
#7MeSH descriptor: [Body Fat Distribution] explode all trees
#8MeSH descriptor: [Body Mass Index] explode all trees
#9MeSH descriptor: [Skinfold Thickness] explode all trees
#10MeSH descriptor: [Waist-Hip Ratio] explode all trees
#11("body weigh*" or bodyweigh* or "body mass*" or bodymass or "body fat*" or bodyfat*):ti,ab
#12MeSH descriptor: [Overnutrition] this term only
#13(overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or over-nutrit*):ti,ab
#14#1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 #11 or #12 or #13
#15MeSH descriptor: [Child] explode all trees
#16MeSH descriptor: [Adolescent] this term only
#17(child* or schoolchild* or preschool* or pre-school* or schoolage* or school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen* or adolescen* or youth* or "young people" or "young person*" or pediatr* or paediatr*):ti,ab
#18#15 or #16 or #17
#19#14 and #18
#20MeSH descriptor: [Exercise] this term only
#21MeSH descriptor: [Exercise Therapy] this term only
#22MeSH descriptor: [Physical Exertion] this term only
#23MeSH descriptor: [Motor Activity] this term only
#24MeSH descriptor: [Sports] this term only
#25(sport*):ti,ab
#26MeSH descriptor: [Physical Education and Training] explode all trees
#27(physical near/3 (activit* or education* or exertion* or training)):ti,ab
#28(exercise*):ti,ab
#29MeSH descriptor: [Diet Therapy] explode all trees
#30((diet or dieting) near/5 (health* or weight*)):ti,ab
#31(calorie near/3 (control or reduc* or restriction)):ti,ab
#32("food choice*"):ti,ab
#33("fat camp*" or "weight loss camp*"):ti,ab
#34("nutrition education") ti,ab
#35MeSH descriptor: [Nutrition Therapy] this term only
#36MeSH descriptor: [Behavior Therapy] this term only
#37MeSH descriptor: [Cognitive Therapy] this term only
#38MeSH descriptor: [Psychotherapy] this term only
#39((behavior* or behavior*) near/3 (therap* or technique* or modif* or intervention*)):ti,ab
#40(cognit* near/3 (therap* or technique*or modif* or intervention*)):ti,ab
#41(CBT) ti,ab
#42(psychotherap* or psycho-therap*) ti,ab
#43MeSH descriptor: [Family Therapy] this term only
#44(family near/3 (therap* or intervention*)):ti,ab
#45(family-based):ti,ab
#46MeSH descriptor: [Sedentary Lifestyle] this term only
#47(sedentary near/3 (lifestyle or behavio*r*)):ti,ab
#48MeSH descriptor: [Video Games] this term only
#49MeSH descriptor: [Television] this term only
#50(television or tv):ti,ab
#51("screen time"):ti,ab
#52(psycho-social or psychosocial):ti,ab
#53MeSH descriptor: [Health Promotion] explode all trees
#54MeSH descriptor: [Health Education] this term only
#55(health* near/3 (promot* or educat* or lifestyle)):ti,ab
#56MeSH descriptor: [Life Style] this term only
#57(lifestyle* or life-style*):ti,ab
#58((video or computer) next game*):ti,ab
#59#20 or #21 or #22 or #23 or #24 or #25 or #26 or #27 or #28 or #29 or #30 or #31 or #32 or #33 or #34 or #35 or #36 or #37 or #38 or #39 or #40 or #41 or #42 or #43 or #44 or #45 or #46 or #47 or #48 or #49 or #50 or #51 or #52 or #53 or #54 or #55 or #56 or #57 or #58
#60#19 and #59

Database of Abstracts of Reviews of Effects (DARE)

2012 (4), searched 15 January 2013 [eight records]
2013 (2), searched 8 May 2013, limited to publication year 2012 to 2013 [16 records]

 #1MeSH descriptor: [Overweight] explode all trees
#2MeSH descriptor: [Body Weight] this term only
#3(obese or obesity or overweight or over-weight):ti,ab
#4MeSH descriptor: [Body Weight Changes] explode all trees
#5(weight near/2 (loss or lost or losing or reduc*)):ti,ab
#6(weight near/2 (gain* or increas*)):ti,ab
#7MeSH descriptor: [Body Fat Distribution] explode all trees
#8MeSH descriptor: [Body Mass Index] explode all trees
#9MeSH descriptor: [Skinfold Thickness] explode all trees
#10MeSH descriptor: [Waist-Hip Ratio] explode all trees
#11("body weigh*" or bodyweigh* or "body mass*" or bodymass or "body fat*" or bodyfat*):ti,ab
#12MeSH descriptor: [Overnutrition] this term only
#13(overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or over-nutrit*):ti,ab
#14#1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 #11 or #12 or #13
#15MeSH descriptor: [Child] explode all trees
#16MeSH descriptor: [Adolescent] this term only
#17(child* or schoolchild* or preschool* or pre-school* or schoolage* or school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen* or adolescen* or youth* or "young people" or "young person*" or pediatr* or paediatr*):ti,ab
#18#15 or #16 or #17
#19#14 and #18
#20MeSH descriptor: [Exercise] this term only
#21MeSH descriptor: [Exercise Therapy] this term only
#22MeSH descriptor: [Physical Exertion] this term only
#23MeSH descriptor: [Motor Activity] this term only
#24MeSH descriptor: [Sports] this term only
#25(sport*):ti,ab
#26MeSH descriptor: [Physical Education and Training] explode all trees
#27(physical near/3 (activit* or education* or exertion* or training)):ti,ab
#28(exercise*):ti,ab
#29MeSH descriptor: [Diet Therapy] explode all trees
#30((diet or dieting) near/5 (health* or weight*)):ti,ab
#31(calorie near/3 (control or reduc* or restriction)):ti,ab
#32("food choice*"):ti,ab
#33("fat camp*" or "weight loss camp*"):ti,ab
#34("nutrition education") ti,ab
#35MeSH descriptor: [Nutrition Therapy] this term only
#36MeSH descriptor: [Behavior Therapy] this term only
#37MeSH descriptor: [Cognitive Therapy] this term only
#38MeSH descriptor: [Psychotherapy] this term only
#39((behavior* or behavior*) near/3 (therap* or technique* or modif* or intervention*)):ti,ab
#40(cognit* near/3 (therap* or technique*or modif* or intervention*)):ti,ab
#41(CBT) ti,ab
#42(psychotherap* or psycho-therap*) ti,ab
#43MeSH descriptor: [Family Therapy] this term only
#44(family near/3 (therap* or intervention*)):ti,ab
#45(family-based):ti,ab
#46MeSH descriptor: [Sedentary Lifestyle] this term only
#47(sedentary near/3 (lifestyle or behavio*r*)):ti,ab
#48MeSH descriptor: [Video Games] this term only
#49MeSH descriptor: [Television] this term only
#50(television or tv):ti,ab
#51("screen time"):ti,ab
#52(psycho-social or psychosocial):ti,ab
#53MeSH descriptor: [Health Promotion] explode all trees
#54MeSH descriptor: [Health Education] this term only
#55(health* near/3 (promot* or educat* or lifestyle)):ti,ab
#56MeSH descriptor: [Life Style] this term only
#57(lifestyle* or life-style*):ti,ab
#58((video or computer) next game*):ti,ab
#59#20 or #21 or #22 or #23 or #24 or #25 or #26 or #27 or #28 or #29 or #30 or #31 or #32 or #33 or #34 or #35 or #36 or #37 or #38 or #39 or #40 or #41 or #42 or #43 or #44 or #45 or #46 or #47 or #48 or #49 or #50 or #51 or #52 or #53 or #54 or #55 or #56 or #57 or #58
#60#19 and #59

SPORTDiscus (EBSCO)

Searched from 1980 to current on 05 March 2012 and 06 May 2013

S66  (S63 and S65)  

S65  S17 and S57 and S64  

S64  S1 or S2 or S3 or S4 or S5 or S6 or S7 or S8 or S9 or S10 or S11 or S12 or S13  

S63  S61 NOT S62 

S62  SU animals NOT SU humans  

S61  (S58 or S59 or S60)  

S60  AB (random* or blind* or allocat* or assign* or trial* or placebo* or crossover or cross-over)  

S59  SU controlled clinical trial  

S58  SU randomized controlled trials 

 S57  (S19 or S20 or S21 or S22 or S23 or S24 or S25 or S26 or S27 or S28 or S29 or S30 or S31 or S32 or S33 or S34 or S35 or S36 or S37 or S38 or S39 or S40 or S41 or S42 or S43 or S44 or S45 or S46 or S47 or S48 or S49 or S50 or S51 or S52 or S53 or S54 or S55 or S56)  

S56  TX ((computer or video or internet) N1 game)  

S55  SU computer game  

S54  TX lifestyle* or life-style*  

S53  TX (health* N3 (lifestyle or promotion or education or behavio?r))  

S52  SU lifestyle  

S51  SU Health Education or SU Health Promotion  

S50  TX psycho-social or psychosocial  

S49  TX "screen time"  

S48  TX television or TV  

S47  SU video games 

S46  SU television  

S45  TX (Sedentary N3 (behavio?r or lifestyle))  

S44  SU Sedentary   

S43  TX family-based  

S42  TX (family N3 (therap* or intervention*))  

S41  SU family therapy  

S40  TX psychotherap* or psycho-therap*  Rerun  View Details Edit Interface -

S39  TX (behavio?r N3 (therap* or technique* or modif* or intervention*))   

S38  TX CBT 

S37  SU Cognitive therapy  

S36  SU Behavior therapy  

S35  SU Psychotherapy    

S34  TX "food choice"  

S33  TX (calorie N3 (control or reduc* or restriction))  

S32  TX ((diet or dieting) N5 (health* or weight*))  

S31  TX "fat camp*" or "weight loss camp*" 

S30  SU food habit  

S29  SU nutrition therapy  

S28  SU diet therapy  

S27  TX exercise*  

S26  TX sport* 

S25  TX (Physical N2 (activit* or education* or training or fitness))  

S24  SU Physical training  

S23  SU Physical activity  

S22  SU Physical education  

S21  SU Sport 

S20  SU Exercise Therapy  

S19  SU Exercise  

S18  (S14 or S15 or S16 or S17)  

S17  TX child* or schoolchild* or preschool* or pre-school* or schoolage* or school-age* or schoolboy* or schoolgirl* or boy* or girl* or preteen* or teen* or adolescen* or youth* or young people or young person* or pediatr* or paediatr*  

S16  SU teenager  

S15  SU adolescent  

S14  SU child  

S13  TX Overeat* or over-eat* or overnourish* or over-nourish* or overnutrit* or over-nutrit* 

S12  TX "waist-hip ratio"  

S11  TX "body weigh*" or bodyweigh* or body mass* or bodymass or "body fat*" or bodyfat*  

S10  TX waist-hip ration  

S9  TX skin fold thickness  

S8  TX body fat distribution  

S7  SU body composition  

S6  TX (weight N2 (gain* or increas*))  

S5  TX (weight N2 (loss or lost or losing or reduc*)) 

S4  TX obes* or overweight or over-weight  

S3  SU body weight change  

S2  SU body weight  

S1  SU overweight  

MIT Cognet searched 23 February 2012 and 06 May 2013

(child* OR adolesc*) AND (obes* OR overweight)

Database on Obesity and Sedentary Behaviour Studies searched 23 February 2012 and 06 May 2013

Child* OR adolesc* OR youth OR boy* Or girl* Or paediatr* OR pediatr*

Database of Promoting Health Effectiveness Reviews (DoPHER) searched 23 February 2012 and 06 May 2013

(Child* OR adolesc* OR youth OR boy* OR girl* OR paediatr* OR pediatr*) AND (obes* OR overweight OR BMI OR “body mass index” OR “body weight change”)

Trials Register of Promoting Health Interventions (TRoPHI) searched 23 February 2012 and 06 May 2013

(child* OR adolesc* OR youth OR boy* OR girl* OR paediatr* OR pediatr*) AND (obes* OR overweight)

Bibliomap searched 23 February 2012 and 06 May 2013

(child* OR adolesc* OR youth OR boy* OR girl* OR paediatr* OR pediatr*)) AND (obes* OR overweight)

www.controlled-trials.com searched 23 February 2012 and 06 May 2013

Obes* child*

Obes* youth

Obes* adolesc*

Overweight child*

www.who.int/trialsearch searched 27 February 2012 and 06 May 2013

Condition: (obes% or overweight) restricted to “Search for clinical trials in children” option

OpenSIGLE (opengray) searched 23 February 2012 and 06 May 2013

(child* OR adolesc* OR youth or boy* or girl*) AND (obes* OR overweight)

Networked Digital Library of Theses and Dissertations searched 28 February 2012 and 06 May 2013

(children OR adolescents OR youth) and (overweight OR obesity) AND (randomised controlled trial)

 

Appendix 2. Summary of school achievement and cognitive function measures and test tools used in included studies


OutcomesTestsCognitive processesStandardised score/scale rangeUnitsScale direction






SCHOOL ACHIEVEMENT

MathematicsCAT-3

W-J Tests of Achievement III

(broad math)
Number concepts, measurement, patterns, data analysis and probability, geometry and spatial sense

Simple and complex calculation skills, math fluency (number facility), mathematical reasoning and problem analysis and solving
M = 500, SD = 70

M = 100, SD = 15

(range zero to 200)

≥ 131 = very superior; 121 to 130 = superior; 111 to 120 = high average; 90 to 110 = average; 80 to 89 = low average; 70 to 79 = low; ≤ 69 = very low
Number of correct answers

Number of correct responses
High = better performance

High = better performance






LanguageCAT-3Sentence structure, writing conventions, paragraph structure, information managementM = 500, SD = 70Number of correct responsesHigh = better performance






ReadingCAT-3

W-J Tests of Achievement III (broad reading)
Reading decoding (letter-word identification), words/phrases in context, reading comprehension (stated information, visual materials, central thought), analysis of text, critical assessment

Reading decoding (letter-word identification), reading fluency (speed), reading comprehension of textual information
M = 500, SD = 70

M = 100, SD = 15

(range zero to 200)

≥ 131 = very superior; 121 to 130 = superior; 111 to 120 = high average; 90 to 110 = average; 80 to 89 = low average; 70 to 79 = low; ≤ 69 = very low
Number of correct responses

Number of correct responses
High = better performance

High = better performance






VocabularyPPVT IIIReceptive vocabulary acquisitionM =100, SD = 15Number of correct responsesHigh = better performance






COGNITIVE FUNCTION

Carroll (1993)Authors of studiesClassification of cognitive domains is challenging because most tests measure abilities in more than one cognitive domain, and therefore overlapping occurs. We chose this classification for two reasons: (1) We referred to what the authors said they would test, and (2) the modified classification by Carroll 1993 was used by another Cochrane Review (Gogia 2012)



GfExecutive functionD–KEFS (Design Fluency and Trail-Making)

CAS (Planning

Scale)
Subscales measure visual–spatial skills, response inhibition, motor planning, visual scanning, speed and cognitive flexibility

Strategy generation and application, self regulation, intentionality and utilisation of knowledge
M = 10, SD = 3

M = 100, SD = 15
Number of correct responses

Sum of total time scale score

and accuracy scale score (ratio of number of correct responses and

total time)
High = better performance

High = better performance






Inhibitory controlKiTAP (Go/No Go Task)ImpulsivityM = 50, SD = 10Reaction time and number of errorsLow = better performance






Working memoryCAS (successive processing)Remembering or completing information in a specific order or sequenceM = 100, SD = 15Sum of number of correct responses scale score and total time scale scoreHigh = better performance






Simultaneous processingaCASNonverbal and verbal processing, analyses and synthesis of logical and grammatical components of language and comprehension of word relationships, nonverbal matrices, verbal spatial relations and figure memoryM = 100, SD = 15Scale score of number of correct responsesHigh = better performance







Speed and processingAttentionCASb

KiTAP
Expressive attention, number detection and receptive attention

Sustained attention including aspects of working memory and mental flexibility
M = 100, SD = 15

M = 50, SD = 10

(range zero to 100)
Sum of scale scores of accuracy one and accuracy two; accuracy one (ratio of number of correct responses and total time); accuracy two (ratio of [number of correct responses minus number of false detections] and total time)

Number of correct
responses based on the difference in maximal numbers of possible errors and omissions
High = better performance

High = better performance



CAT-3: Canadian Achievement Test, version 3; W-J: Woodcock-Johnson; PPVT III: Peabody Picture Vocabulary Test, version 3; CAS: Das-Naglieri-Cognitive Assessment System; KiTAP: [Kinderversion der Testbatterie zur Aufmerksamkeitsprüfung] Attention test battery for children; D–KEFS: Delis-Kaplan Executive Function System. aSimultaneous processing includes tests of memory and executive function. bCAS also includes measures that could be categorised as speed or executive function.

 

Contributions of authors

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms

All review authors contributed to the development of this protocol. AM and DHS drafted the protocol, with significant input from SDS and JS. AM, DHS and SDS developed the search strategy. AM and DHS screened the titles and abstracts of potentially eligible studies and reports and assessed the full report of potentially relevant studies for eligibility, in consensus with SDS and JS when necessary. AM drafted the full review with regular input from all review authors.

 

Declarations of interest

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms

  • Anne Martin - none known.
  • David H Saunders - none known.
  • Susan D Shenkin - none known.
  • John Sproule - none known.

 

Sources of support

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms
 

Internal sources

  • The University of Edinburgh, UK.
    The University of Edinbugh provided support in the form of salaries for DHS, SDS and JS; support in the form of a PhD scholarship for AM; and support for attendance at the UK Cochrane Training Courses by AM via staff development funds

 

External sources

  • No sources of support supplied

 

Differences between protocol and review

  1. Top of page
  2. Summary of findings    [Explanations]
  3. Background
  4. Objectives
  5. Methods
  6. Results
  7. Discussion
  8. Authors' conclusions
  9. Acknowledgements
  10. Data and analyses
  11. Appendices
  12. Contributions of authors
  13. Declarations of interest
  14. Sources of support
  15. Differences between protocol and review
  16. Index terms

We intended from the outset to select studies based on inclusion criteria; however, we did not state this explicitly in the protocol. The intervention criterion for inclusion was that the study aimed to prevent or treat childhood obesity as a primary or secondary outcome through lifestyle interventions. The outcome criterion for inclusion was that studies measured school achievement, cognitive function and future success as defined in Types of outcome measures.

We stated in the protocol that studies that included some overweight children would be included in the review only when outcomes for overweight or obese children were reported separately. Only a few studies investigated the effects of lifestyle interventions on school achievement and/or cognitive function in an overweight paediatric population; therefore we did not exclude those studies if results for this population group were not reported separately. We put all efforts in place and contacted the authors of those studies to obtain data for the overweight and/or obese subgroup.

In the protocol, we stated that we would include controlled trials. We intended to include controlled clinical trials as defined by the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011); we did not intend to include non-randomised controlled trials.

For continuous outcomes measured on different scales and reported as both change data and postintervention data, we analysed the treatment effect by calculating the mean difference. We did not explicitly state this possibility in the protocol.

We provided effect sizes for studies that were inappropriate for inclusion in a meta-analysis. The protocol stated that we would provide a narrative description of study results derived from those studies.

* Indicates the major publication for the study

References

References to studies included in this review

  1. Top of page
  2. AbstractRésumé scientifique摘要
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. References to ongoing studies
  22. Additional references
Ahamed 2007 {published and unpublished data}
  • Ahamed Y, Macdonald H, Reed K, Naylor PJ, Liu-Ambrose T, McKay H. School-based physical activity does not compromise children's academic performance. Medicine and Science in Sports and Exercise 2007;39(2):371-6.
  • Naylor PJ, Macdonald HM, Zebedee JA, Reed KE, McKay HA. Lessons learned from Action Schools! BC - An 'active school' model to promote physical activity in elementary schools. Journal of Science and Medicine in Sport 2006;9(5):413-23.
  • Naylor PJ, Scott J, Drummond J, Bridgewater L, McKay HA, Panagiotopoulos C. Implementing a whole school physical activity and healthy eating model in rural and remote first nations schools: a process evaluation of action schools! BC. Rural and Remote Health 2010;10(2):1296.
  • Reed KE, Warburton DER, Macdonald HM, Naylor PJ, McKay HA. Action Schools! BC: a school-based physical activity intervention designed to decrease cardiovascular disease risk factors in children. Preventive Medicine 2008;46(6):525-31.
Davis 2011 {published data only}
  • Davis CL, Pollock NK, Waller JL, Allison JD, Dennis BA, Bassali R, et al. Exercise dose and diabetes risk in overweight and obese children: a randomized controlled trial. JAMA 2012;308(11):1103-12.
  • Davis CL, Tomporowski PD, Boyle CA, Waller JL, Miller PH, Naglieri JA, et al. Effects of aerobic exercise on overweight children's cognitive functioning: a randomized controlled trial. Research Quarterly for Exercise and Sport 2007;78(5):510-9.
  • Davis CL, Tomporowski PD, McDowell JE, Austin BP, Miller PH, Yanasak NE, et al. Exercise improves executive function and achievement and alters brain activation in overweight children: a randomized, controlled trial. Health Psychology 2011;30(1):91-8.
  • Tkacz J, Young-Hyman D, Boyle CA, Davis CL. Aerobic exercise program reduces anger expression among overweight children. Pediatric Exercise Science 2008;20(4):390-401.
Johnston 2013 {published data only}
Staiano 2012 {published data only}
  • Exner AL. Impact of cooperative versus competitive exergame play on overweight and obese adolescents' physical, socio-emotional, and cognitive health. Dissertation Abstracts International: Section B: The Sciences and Engineering 2011;72(2-B):1193.
  • Staiano AE, Abraham AA, Calvert SL. Competitive versus cooperative exergame play for African American adolescents' executive function skills: short-term effects in a long-term training intervention. Developmental Psychology 2012;48(2):337-42.
Winter 2011 {published and unpublished data}
  • Winter SM, Sass DA. Healthy & ready to learn: examining the efficacy of an early approach to obesity prevention and school readiness. Journal of Research in Childhood Education 2011;25(3):304-25.
Wirt 2013 {unpublished data only}
  • Dreyhaupt J, Koch B, Wirt T, Schreiber A, Brandstetter S, Kesztyus D, et al. Study protocol: evaluation of a health promotion program in children: study protocol and design of the cluster-randomized Baden-Wurttemberg primary school study [DRKS-ID: DRKS00000494]. BMC Public Health 2012;12:157.
  • Wirt T, Schreiber A, Dreyhaupt J, Kesztyues D, Hundsdoerfer V, Steinacker JM. Health promotion in primary schools and cognitive performance - evaluation of transfer effects of a school based programme [personal communication]. Email to: Anne Martin 28 February 2013.

References to studies excluded from this review

  1. Top of page
  2. AbstractRésumé scientifique摘要
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. References to ongoing studies
  22. Additional references
Bartholomew 2011 {published data only}
Chaya 2012 {published data only}
  • Chaya MS, Nagendra H, Selvam S, Kurpad A, Srinivasan K. Effect of yoga on cognitive abilities in schoolchildren from a socioeconomically disadvantaged background: a randomized controlled study. Journal of Alternative and Complementary Medicine 2012;18(12):1161-7.
Delgado-Rico 2012b {published data only}
  • Delgado-Rico E, Rio-Valle JS, Albein-Urios N, Caracuel A, González-Jiménez E, Piqueras MJ, et al. Effects of a multicomponent behavioral intervention on impulsivity and cognitive deficits in adolescents with excess weight. Behavioural Pharmacology 2012;23(5-6):609-15.
Epstein 2000 {published data only}
Grieco 2009 {published data only}
  • Grieco LA, Jowers EM, Bartholomew JB. Physically active academic lessons and time on task: the moderating effect of body mass index. Medicine and Science in Sports and Exercise 2009;41(10):1921-6.
Gunnarsdottir 2012b {published data only}
Hill 2011 {published data only}
Hollar 2010 {published data only}
  • Hollar D, Messiah SE, Lopez-Mitnik G, Hollar T, Almon M, Agatston AS. Effect of a two-year obesity prevention intervention on percentile changes in body mass index and academic performance in low-income elementary school children. American Journal of Public Health 2010;100(4):646-53.
Hutson 2008 {published data only}
  • Hutson JB. The Relationship between Adolescent Obesity Treatment and Academic Performance [Thesis]. ProQuest, 2008.
Leidy 2013 {published and unpublished data}
  • Leidy H. The beneficial effects of a protein-rich breakfast on appetite control & cognition in overweight and obese adolescents. http://clinicaltrials.gov/show/NCT01192100 (accessed 21 October 2013).
Milosis 2007 {published data only}
  • Milosis D, Papaioannou AG. Interdisciplinary teaching, multiple goals and self-concept. In: Liokkonen J, Vanden Auweele Y, Vereijken B, Theodorakis Y editor(s). Psychology for Physical Educators: Student in Focus. 2nd Edition. Champaign, IL: Human Kinetics, 2007:175-98.
Reed 2012 {published data only}
  • Reed JA, Maslow AL, Long S, Hughey M. Examining the impact of 45 minutes of daily physical education on cognitive ability, fitness performance, and body composition of African American youth. Journal of Physical Activity & Health 2013; Vol. 10, issue 2:185-97.
Robinson 2010 {published data only}
  • Robinson TN, Matheson DM, Kraemer HC, Wilson DM, Obarzanek E, Thompson NS, et al. A randomized controlled trial of culturally tailored dance and reducing screen time to prevent weight gain in low-Income African American Girls: Stanford GEMS. Archives of Pediatrics & Adolescent Medicine 2010;164(11):995-1004.
Tomporowski 2008 {published data only}
  • Tomporowski PD, Davis CL, Lambourne K, Gregoski M, Tkacz J. Task switching in overweight children: effects of acute exercise and age. Journal of Sport & Exercise Psychology 2008;30(5):497-511.
Vanhelst 2012 {published data only}
  • Vanhelst J, Beghin L, Fardy PS, Bui-Xuan G, Mikulovic J. A conative educational model for an intervention program in obese youth. BMC Public Health 2012;12:416.
  • Vanhelst J, Marchand F, Fardy P, Zunquin G, Loeuille GA, Renaut H, et al. The CEMHaVi program: control, evaluation, and modification of lifestyles in obese youth. Journal of Cardiopulmonary Rehabilitation and Prevention 2010;30(3):181-5.
Verbeken 2013 {published data only}
  • Verbeken S, Braet C, Goossens L, Van der Oord S. Executive function training with game elements for obese children: a novel treatment to enhance self-regulatory abilities for weight-control. Behaviour Research and Therapy 2013;51(6):290-9.
Vos 2011 {published data only}
  • Vos RC, Wit JM, Pijl H, Kruyff CC, Houdijk ECAM. The effect of family-based multidisciplinary cognitive behavioral treatment in children with obesity: study protocol for a randomized controlled trial. Trials 2011;12:110.

References to studies awaiting assessment

  1. Top of page
  2. AbstractRésumé scientifique摘要
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. References to ongoing studies
  22. Additional references
Coe 2006 {published data only}
  • Coe DP, Pivarnik JM, Womack CJ, Reeves MJ, Malina RM. Effect of physical education and activity levels on academic achievement in children. Medicine and Science in Sports and Exercise 2006;38(8):1515-9.
Donnelly 2009 {published data only}
  • Donnelly JE, Greene JL, Gibson CA, Smith BK, Washburn RA, Sullivan DK, et al. Physical Activity Across the Curriculum (PAAC): a randomized controlled trial to promote physical activity and diminish overweight and obesity in elementary school children. Preventive Medicine 2009; Vol. 49, issue 4:336-41.
  • Donnelly JE, Lambourne K. Classroom-based physical activity, cognition, and academic achievement. Preventive Medicine 2011;52(42):S36-42.
Murray 2008 {published data only}
  • Murray NG, Garza JC, Diamond PM, Stigler MH, Hoelscher D, Kelder S, et al. PASS & CATCH improves academic achievement. www.nemours.org/content/dam/nemours/wwwv2/filebox/service/healthy-living/growuphealthy/makeschoolmove/educators/take10/passcatch.pdf (accessed 21 October 2013).
Puder 2011 {published data only}
  • Niederer I, Bürgi F, Ebenegger V, Marques-Vidal, Schindler C, Nydegger A, et al. Effects of a lifestyle intervention on adiposity and fitness in overweight or low fit preschoolers (Ballabeina). Obesity 2013;21(3):E287-93.
  • Niederer I, Kriemler S, Zahner L, Burgi F, Ebenegger V, Hartmann T, et al. Influence of a lifestyle intervention in preschool children on physiological and psychological parameters (Ballabeina): study design of a cluster randomized controlled trial. BMC Public Health 2009;9:94.
  • Puder JJ, Marques-Vidal P, Schindler C, Zahner L, Niederer I, Ebenegger V, et al. Effect of multidimensional lifestyle intervention on fitness and adiposity in predominantly migrant preschool children (Ballabeina): cluster randomised controlled trial. BMJ 2011;343(7830):945.
Reed 2010 {published data only}
  • Reed JA, Einstein G, Hahn E, Hooker SP, Gross VP, Kravitz J. Examining the impact of integrating physical activity on fluid intelligence and academic performance in an elementary school setting: a preliminary investigation. Journal of Physical Activity & Health 2010;7(3):343-51.
Telford 2012 {published data only}
  • Telford RD, Cunningham RB, Fitzgerald R, Olive LS, Prosser L, Jiang X, et al. Physical education, obesity, and academic achievement: a 2-year longitudinal investigation of Australian elementary school children. American Journal of Public Health 2012;102(2):368-74.

References to ongoing studies

  1. Top of page
  2. AbstractRésumé scientifique摘要
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. References to ongoing studies
  22. Additional references
Accacha 2012 {published and unpublished data}
  • Accacha S, Corletto J, Fiore E. Insulin resistance and cognitive dysfunction on obese adolescents: pilot study. http://clinicaltrials.gov/show/NCT01737658 (accessed 21 October 2013).
Andersen 2012 {published and unpublished data}
  • Andersen LB. The Odense Overweight Intervention Study (OOIS). http://clinicaltrials.gov/show/NCT01574352 (accessed 21 October 2013).
Damsgaard 2012 {published data only}
  • Damsgaard CT, Dalskov SM, Petersen RA, Sørensen LB, Mølgaard C, Biltoft-Jensen A, et al. Design of the OPUS School Meal Study: a randomised controlled trial assessing the impact of serving school meals based on the New Nordic Diet. Scandinavian Journal of Public Health 2012;40(8):693-703.
Donnelly 2012 {published and unpublished data}
  • Donnelly J. Physical Activity and Academic Achievement Across the Curriculum (A+PAAC). http://clinicaltrials.gov/show/NCT01699295 (accessed 21 October 2013).
Martinez-Vizcaino 2012 {published data only}
  • Martinez-Vizcaino V, Sanchez-Lopez M, Salcedo-Aguilar F, Notario-Pacheco B, Solera- Martínez M, Moya-Martínez M, et al. Protocol of a randomized cluster trial to assess the effectiveness of the MOVI-2 program on overweight prevention in schoolchildren [Protocolo de un ensayo aleatorizado de clusters para evaluar la efectividad del programa MOVI-2 en la prevencion del sobrepeso en escolares]. Revista Española de Cardiología 2012;65(5):427-33.
Pentz 2011 {published data only}
  • Pentz MA, Huh J, Riggs NR, Spruijt-Metz D, Chou CP. Effects of a childhood obesity prevention program aimed at executive cognitive function: the pathways trial. Obesity. Proceedings of the 29th Annual Scientific Meeting of the Obesity Society; 2011 October 1-5; Orlando (FL). 2011:S121.
Robinson 2012 {published and unpublished data}
  • Robinson TN, Matheson D. Clinic, family and community collaboration to treat overweight and obese children (Stanford GOALS). http://clinicaltrials.gov/show/NCT01642836 (accessed 21 October 2013).
Tompkins 2012 {published data only}
  • Tompkins CL, Hopkins J, Goddard L, Brock DW. The effect of an unstructured, moderate to vigorous, before-school physical activity program in elementary school children on academics, behavior, and health. BMC Public Health 2012;12:300.

Additional references

  1. Top of page
  2. AbstractRésumé scientifique摘要
  3. Summary of findings
  4. Background
  5. Objectives
  6. Methods
  7. Results
  8. Discussion
  9. Authors' conclusions
  10. Acknowledgements
  11. Data and analyses
  12. Appendices
  13. Contributions of authors
  14. Declarations of interest
  15. Sources of support
  16. Differences between protocol and review
  17. Characteristics of studies
  18. References to studies included in this review
  19. References to studies excluded from this review
  20. References to studies awaiting assessment
  21. References to ongoing studies
  22. Additional references
Beebe 2010
  • Beebe DW, Ris MD, Kramer ME, Long E, Amin R, Beebe DW, et al. The association between sleep disordered breathing, academic grades, and cognitive and behavioral functioning among overweight subjects during middle to late childhood. Sleep 2010;33(11):1447-56.
Belot 2011
Brixval 2012
  • Brixval CS, Rayce SL, Rasmussen M, Holstein BE, Due P. Overweight, body image and bullying - an epidemiological study of 11- to 15-years olds. European Journal of Public Health 2012;22(1):126-30.
Bruce 2011
Caird 2011
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Calcaterra 2008
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Davis 2012
  • Davis CL, Pollock NK, Waller JL, Allison JD, Dennis BA, Bassali R, et al. Exercise dose and diabetes risk in overweight and obese children: a randomized controlled trial. JAMA 2012;308(11):1103-12.
Delgado-Rico 2012a
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Fields 2013
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Gogia 2012
Gomez-Pinilla 2008
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Gunnarsdottir 2012a
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Gupta 2012
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