Commercial weight loss products and services for obese and overweight adults

  • Protocol
  • Intervention

Authors


Abstract

This is the protocol for a review and there is no abstract. The objectives are as follows:

To assess the effects of commercial weight loss products and services for overweight or obese people.

Background

There are a wide range of commercial weight loss options available to the general public, which vary in cost. It is not known which products and services offer the most effective and cost-effective results for weight loss and maintenance.

Description of the condition

Overweight and obesity are major preventable health burdens facing most middle and high income countries. Both overweight and obesity are defined as excessive fat accumulation that presents a risk to health (WHO 2013).

Trends indicate that a shift in energy balance, predominately excess energy intake exceeding energy expenditure rather than changes in our gene pool have led to the high levels of obesity and overweight we see in many countries (WHO 2013).

The body mass index (BMI) is the preferred method of body fat measurement in clinical settings, for practicality, and cost effectiveness to illustrate the health risks associated with a raised BMI (Gray 1991). However, BMI as a measurement method is only a proxy measure of body fatness. BMI is a measure of weight relative to height, calculated by dividing weight (kg) by height (m2) (Foresight 2007). The World Health Organization (WHO) has identified particular cut-off points for the classification of underweight, ideal, overweight and obese adults (WHO 2006).

Underweight is defined as BMI < 18.5, normal weight is BMI 18.5 to 24.9, and overweight is BMI 25 to 29.9. Obesity is classified in three categories: class I obesity (BMI 30.0 to 34.9), class II obesity (BMI 35.0 to 39.9), and class III - morbid obesity (≥ 40.0). BMI must be used with caution: This method of measurement assesses total body weight irrespective of muscle and fat mass. Certain populations (elderly and athletes) could fall into incorrect categories in recognition of their BMI classification. 

WHO has identified intermediate action points for Asian populations. However, these are not universal across all ethnicities. Studies that have included non-Caucasian populations should use BMI adjusted calculations for the participants involved.

Ideally, additional methods of assessment should be utilised to predict health risks associated with an increased fat mass (waist circumference and waist-to-hip ratio). However, caution should be used. Defined waist circumference protocols (minimal waist, umbilicus, immediately above the iliac crest, and midpoint point between the lowest rib and immediately above the iliac crest) correlate with different health related risk factor cut-off points.

The prevalence of obesity and overweight is not confined to Western populations. Deprived and developing countries have observed malnutrition equalling obesity (Lobstein 2004). Globally it is estimated that by 2015, approximately 700 million adults will be obese, and 2.3 billion will be overweight. If trends do not subside, 50% of the United Kingdom’s population could be defined as obese by 2050 (Foresight 2007). There are indications from some countries that the rate of increase may have plateaued, for example in the US at about a third of the population (Flegal 2010). One in 10 five to seventeen year olds are classified as overweight, a total of 155 million, and 1 in 50 are classified as obese which accounts for 30 to 45 million of the presented figure (Lobstein 2004). The National Child Measurement Programme (NCMP) data set of four to five year olds and 10 to 11 year olds in England, 2009/2010 reported that in 23.1% of the younger children measured were either overweight or obese, one in three (33.4%) of the older children measured were either overweight or obese (Health and Social Care Information Centre 2010).

Obesity accounts for a plethora of physical, social and psychological consequences, and is associated with type 2 diabetes, hypertension, congestive heart failure, certain cancers, and non-alcoholic fatty liver disease. Obesity is also associated with early mortality (National Audit Office 2001).

Financial costs incurred to the individual and the state account for a considerable amount of state expenditure regardless of the country of origin. Indirect effects of obesity can be measured, calculating increased number of sick days, earlier retirement, decreased performance, loss of earnings, and loss of productivity and capability. Direct costs relate to the prevention, diagnosis and treatment of obesity.

At an individual level, increases in the consumption of whole grains, nuts, legumes, fruits, vegetables and physical activity is recommended, paralleled with the limitation of total fats, and reduced intake of sugars.

As a result of the rise in obesity prevalence, the search for cost-effective interventions is of paramount importance. Numerous treatment options are available via primary care providers, and available for purchase at an individual level, including bariatric surgery, pharmacological interventions, behaviour modification, and commercial alternatives.

Lowe 2001 report an increasing amount of overweight individuals who seek treatment in the commercial environment. However, insufficient evidence supports long-term effectiveness of commercial interventions (Ditschuneit 2001; Foster 2003; Heshka 2003). Research traditionally lies within short-term studies, reporting effectiveness of commercial alternatives (Heshka 2000).

Discontinuation of a commercial treatment option results in weight regain in 33% to 66% of individuals within the first year, and the majority of lost weight is regained within five years (Lowe 2001), warranting the requirement of effective long-term evaluation and research.

Some of the most recognisable commercial weight loss products and services have been established for only four decades. The last 10 years have seen the companies who produce and deliver these products and services strengthening their delivery, marketing strategies, and the sharing of results with the rest of the weight loss industry. It is uncertain whether commercial weight loss products and services are a cost effective method for weight loss maintenance (Gosselin 2001).

Within the United Kingdom, some primary care trusts have offered a referral option to commercial weight loss programmes, such as Weight Watchers (http://www.weightwatchers.com/) and Slimming World (http://www.slimmingworld.com/), but often for just a duration of12 weeks. Literature does not specifically illustrate why certain programmes have been favoured over others, other than their popularity in the public domain. As the value of the commercial sector which aims to help people lose weight continues to rise (it currently exceeds £2 billion (€2.3 billion) (Foresight 2007), it is of paramount importance to conduct research in relation to effectiveness of commercial weight loss products and services and translate this information to policy and practice so that they, and the public, can make better informed treatment choices.

Description of the intervention

Commercial weight loss products and services have increased in number, patterned with rising obesity and overweight prevalence (Hamilton 2004). Marketing of these products and services has been observed in various venues and advertising spaces, including online. There is a wealth of choice available to users in terms of types of products and services available for adults, including dietary supplements, own-brand groceries, meal replacement products, menu guides combined with food planning, and food calorie points systems. Numerous popular products and services focus on group support, led by an individual who has succeeded in the programme, and is maintaining their weight. Individuals who wish to lose weight through commercial weight loss products and services have a considerable amount of choices. Evidence to justify weight maintenance is overwhelmed by marketing strategies. Specifically for this systematic review, we will concentrate upon interventions that are commercial weight loss products and services which deliver advice via a number of settings and media (e.g. face to face group settings, online) where advice is restricted to diet and/or physical activity behaviour change, including meal replacements. The review will not include products and services which include weight loss drugs, hypnotherapy or hypnosis, incentives, or nutriceuticals.

Adverse effects of the intervention

Research has not specifically examined the adverse effects of commercial weight loss products and services, systematic assessment is required. Specifically, we will include information in relation to attrition and uptake of said interventions.

How the intervention might work

Increasing number of people turn to the commercial market for weight loss treatment (Lowe 2001). Research suggests that weight loss maintenance could be more effective for individuals who start a group-based behavioural treatment programme (Akers 2010). However, individual based programmes have also shown positive results (Rock 2010). Techniques taught by the programmes reviewed could be more successful in relapse prevention and problem solving. The format of the programme could also impact upon weight and BMI changes.

Why it is important to do this review

Advice on weight loss from primary care providers has been shown to be effective (Levy 1988). Individuals who wish to gain guidance and advice from a practitioner in relation to commercial weight loss products and services are often not able to do so, practitioners may feel ill equipped to confidently provide this information (Tsai 2005). In order to assist practitioners, and prior to selecting a commercial weight loss product or service, systematic synthesis of evidence is required. Commercial weight loss products and services are limited in number. However, short-term effectiveness has been demonstrated (Heshka 2000). Primarily, consumers and practitioners require information concerning cost-effectiveness, ascertaining how much a product or service costs for a prescribed and advised intervention period (12 weeks), and whether weight will be regained after the individual has discontinued with the product or service.

Commercial weight loss treatment options require evaluation to assess effectiveness, and to assist commissioners of service. This evidence is equally important for users in order to help them choose a method that is based upon evidence rather than marketing strategies.

Health inequalities could be tackled by marketing of commercial weight loss interventions targeting individuals with lower socio-economic status. Research suggests that socio-economic status is patterned with obesity and overweight prevalence (House of Commons Health Committee 2004). Specific areas of the United Kingdom with low socio-economic status, and increased deprivation could be widening the health inequalities gap via differential purchase of commercial weight loss treatment options.

Objectives

To assess the effects of commercial weight loss products and services for overweight or obese people.

Methods

Criteria for considering studies for this review

Types of studies

We will include randomised controlled trials (RCTs) and controlled clinical trials.

Types of participants

We will include males and/or females aged 18 years or older. Trials which focus on pregnant and lactating women will be excluded.

Types of interventions

We will include Interventions which have been conducted for a minimum of six months, one year, and beyond where data available.

Intervention

Commercial weight loss products and services which deliver advice via a number of settings and media (e.g. face to face group settings, online) where advice is restricted to diet and/or physical activity behaviour change, including meal replacements(interventions which include weight loss drugs, hypnotherapy or hypnosis, incentives, or nutriceuticals will not be included). 

Control
  • Placebo.

  • Usual care.

  • Another commercial weight loss product or service.

Types of outcome measures

Primary outcomes
  • Weight change and change in BMI at one year.

  • Health-related quality of life (measured by a validated instrument).

  • Adverse effects.

Secondary outcomes
  • Change data at six months, one year, and beyond where data are available for weight, BMI, percentage overweight and obese, waist-to-hip ratio, waist circumference, cholesterol (total cholesterol, high-density lipoprotein (HDL)-cholesterol, low-density lipoprotein (LDL)-cholesterol), and blood pressure (diastolic and systolic).

  • Costs (delivery and cost effectiveness).

  • All-cause mortality.

  • Morbidity.

  • Compliance with commercial weight loss product or service.

  • Attrition.

Timing of outcome measurement

Outcomes measured at around six months, one year, and beyond where data are available will be included.

'Summary of findings' table

We will present a 'Summary of findings table' reporting the following outcomes listed according to priority.

  1. Health-related quality of life.

  2. Morbidity.

  3. All-cause mortality.

  4. Adverse effects.

  5. Compliance.

  6. Change in weight measure.

  7. Costs.

Search methods for identification of studies

Electronic searches

We will search the following sources from inception to the present.

  • The Cochrane Library.

  • MEDLINE.

  • EMBASE.

  • CINAHL.

  • PsycINFO.

We will also search databases of ongoing trials including ClinicalTrials.gov (http://clinicaltrials.gov/), metaRegister of Controlled Trials (http://www.controlled-trials.com/mrct/), the EU Clinical Trials register (https://www.clinicaltrialsregister.eu/) and the WHO International Clinical Trials Registry Platform Search Portal (http://apps.who.int/trialsearch/).

For detailed search strategies see Appendix 1. We will continuously apply PubMed's 'My NCBI' (National Center for Biotechnology Information) email alert service to identify newly published studies using a basic search strategy (Appendix 1). Four weeks before we submit the final review draft to the Cochrane Metabolic and Endocrine Disorders Group for editorial approval, we will perform an updated search on all specified databases. If we identify new studies for inclusion we will evaluate these and incorporate findings in our review before submission of the final review draft.

If we detect additional relevant key words during any of the electronic or other searches, we will modify the electronic search strategies to incorporate these terms and document the changes. We will place no restrictions on the language of publication when searching the electronic databases or reviewing reference lists in identified studies.

We will send results of electronic searches to the Cochrane Metabolic and Endocrine Disorders Group for databases which are not available at the editorial office.

Searching other resources

We will try to identify other potentially eligible trials or ancillary publications by searching the reference lists of retrieved included trials, (systematic) reviews, meta-analyses and health technology assessment reports.

Data collection and analysis

Selection of studies

To determine the studies to be assessed further, two authors (AC, CS) will independently scan the abstract, title or both sections of every record retrieved. All potentially relevant articles will be investigated as full text. Where differences in opinion exist, they will be resolved by a third author (NN). If resolving disagreement is not possible, the article will be added to those 'awaiting assessment' and we will contact authors for clarification. We will present an adapted Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram of study selection (Figure 1) (Liberati 2009).

Figure 1.

Study flow diagram.

Data extraction and management

For studies that fulfil inclusion criteria, two authors (AC, CS) will independently abstract relevant population and intervention characteristics using standard data extraction templates, with any disagreements to be resolved by discussion, or if required by a third author (Table 1; Appendix 2; Appendix 3; Appendix 4; Appendix 5; Appendix 6; Appendix 7; Appendix 8; Appendix 9; Appendix 10; Appendix 11; Appendix 12).

Table 1. Overview of study populations
  1. aAccording to power calculation in study publication or report

    bDuration of intervention and/or follow-up under randomised conditions until end of study

    "-" denotes not reported

    ITT: intention-to-treat; N/A: not applicable

CharacteristicIntervention(s) and comparator(s)Sample sizea[N] Screened/eligible[N] Randomised[N] Safety[N] ITT[N] Finishing study[%] Randomised finishing studyFollow-upb
(1) Study IDIntervention 1        
Intervention 2        
Comparator 1        
Comparator 2        
  total:      
 
Grand total All interventions    ...    ...   
All comparators    ...    ...   
All interventions and comparators    ...    ...   

We will provide information including trial identifier about potentially-relevant ongoing studies in the 'Characteristics of ongoing studies' section and in the appendix 'Matrix of study endpoints (protocol/trial documents)'. We will try to find the protocol of each included study, either in databases of ongoing trials, in publications of study designs, or both, and specify data in the appendix 'Matrix of study endpoints (trial documents)'.

We will send an email to all study authors of included studies to enquire whether they are willing to answer questions regarding their trials. We will present the results of this survey in Appendix 13. Thereafter, we will seek relevant missing information on the trial from the primary author(s) of the article, if required.

Dealing with duplicate publications

In the event of duplicate publications, companion documents or multiple reports of a primary study, we will maximise yield of information by collating all available data. In case of doubt the publication reporting the longest follow-up associated with our primary or secondary outcomes will be given priority.

Assessment of risk of bias in included studies

Two authors (AC, CS) will assess each trial independently. Possible disagreements will be resolved by consensus. In cases of disagreement, the rest of the group will be consulted and a judgement will be made based on consensus.

We will assess risk of bias using the Cochrane Collaboration's tool for assessing risk of bias (Higgins 2011a; Higgins 2011b). We will use the following criteria.

  • Random sequence generation (selection bias).

  • Allocation concealment (selection bias).

  • Blinding (performance bias and detection bias), separated for blinding of participants and personnel and blinding of outcome assessment.

  • Incomplete outcome data (attrition bias).

  • Selective reporting (reporting bias).

  • Other bias.

We will assess outcome reporting bias by integrating the results of 'Examination of outcome reporting bias' (Appendix 7), 'Matrix of study endpoints (protocol/trial documents)' (Appendix 6) and section 'Outcomes (outcomes reported in abstract of publication)' of the 'Characteristics of included studies' section (Kirkham 2010). This analysis will form the basis for the judgement of selective reporting (reporting bias).

We will judge risk of bias criteria as 'low risk', 'high risk' or 'unclear risk' and evaluate individual bias items as described in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a). We will present a 'Risk of bias' figure and a 'Risk of bias summary' figure.

We will assess the impact of individual bias domains on study results at endpoint and study levels.

For blinding of participants and personnel (performance bias), detection bias (blinding of outcome assessors) and attrition bias (incomplete outcome data) we intend to evaluate risk of bias separately for subjective and objective outcomes (Hróbjartsson 2013). We will consider the implications of missing outcome data from individual participants.

We define the following endpoints as subjective outcomes.

  • Health-related quality of life.

  • Adverse effects.

  • Compliance with commercial weight loss product or service.

We define the following outcomes as objective outcomes.

  • Weight change and change in BMI.

  • Change data for percentage overweight and obese, waist-to-hip ratio, waist circumference, cholesterol (total cholesterol, HDL-cholesterol, LDL-cholesterol), and blood pressure (diastolic and systolic).

  • Costs (delivery and cost effectiveness).

  • All-cause mortality.

  • Morbidity.

  • Attrition.

Measures of treatment effect

We will express dichotomous data as odds ratios (ORs) or risk ratios (RRs) with 95% confidence intervals (CIs). We will express continuous data as mean differences (MD) with 95% CIs.

Unit of analysis issues

We will take into account the level at which randomisation occurred, such as cross-over trials, cluster-randomised trials and multiple observations for the same outcome.

Dealing with missing data

We will obtain relevant missing data from authors, if feasible and carefully perform evaluation of important numerical data such as screened, randomised patients as well as intention-to-treat (ITT), as-treated and per-protocol populations. We will investigate attrition rates, for example drop-outs, losses to follow up and withdrawals and critically appraise issues of missing data and imputation methods (for example last-observation-carried-forward (LOCF)).

Assessment of heterogeneity

In the event of substantial clinical, methodological or statistical heterogeneity, we will not report study results as meta-analytically pooled effect estimates.

We will identify heterogeneity by visual inspection of the forest plots and by using a standard Chi2 test with a significance level of α = 0.1, in view of the low power of this test. We will examine heterogeneity using the I2 statistic, which quantifies inconsistency across studies to assess the impact of heterogeneity on the meta-analysis (Higgins 2002; Higgins 2003), where an I2 statistic of 75% or more indicates a considerable level of inconsistency (Higgins 2011a).

When we find heterogeneity, we will attempt to determine potential reasons for it by examining individual study and subgroup characteristics.

We expect the following characteristics to introduce clinical heterogeneity.

  • Co-morbidities such as diabetes mellitus, cancer, respiratory problems, and over- or under active thyroid could contribute to increases or decreases in weight or body mass index.   

  • Compliance to the weight loss product or service.

  • Co-medications.

  • Psychological issues.

Assessment of reporting biases

If we include 10 studies or more for a given outcome, we will use funnel plots to assess small study effects. Owing to several possible explanations for funnel plot asymmetry, we will interpret results carefully (Sterne 2011).

Data synthesis

Unless there is good evidence for homogeneous effects across studies, we will primarily summarise low risk of bias data by means of a random-effects model (Wood 2008). We will interpret random-effects meta-analyses with due consideration of the whole distribution of effects, ideally by presenting a prediction interval (Higgins 2009). A prediction interval specifies a predicted range for the true treatment effect in an individual study (Riley 2011). In addition, we will perform statistical analyses according to the statistical guidelines contained in the latest version of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011a).

Subgroup analysis and investigation of heterogeneity

We will carry out the following subgroup analyses and plan to investigate interaction.

  • Obesity and morbidly obese participants.

  • Overweight and obese participants.

  • Socio-economic status.

  • Gender.

  • Ethnicity.

  • Age.

Sensitivity analysis

We will perform sensitivity analyses in order to explore the influence of the following factors (when applicable) on effect sizes.

  • Restricting the analysis to published studies.

  • Restricting the analysis taking into account risk of bias, as specified in the section Assessment of risk of bias in included studies.

  • Restricting the analysis to very long or large studies to establish how much they dominate the results.

  • Restricting the analysis to studies using the following filters: diagnostic criteria, language of publication, source of funding (industry versus other), country.

We will also test the robustness of the results by repeating the analysis using different measures of effect size (RR, OR etc.) and different statistical models (fixed-effect and random-effects models).

Appendices

Appendix 1. Search strategies

Search terms and databases

Unless otherwise stated, search terms are free text terms.

Abbreviations:

'$': stands for any character; '?': substitutes one or no character; adj: adjacent (i.e. number of words within range of search term); exp: exploded MeSH; MeSH: medical subject heading (MEDLINE medical index term); pt: publication type; sh: MeSH; tw: text word.

The Cochrane Library
#1 MeSH descriptor Obesity explode all trees
#2 MeSH descriptor Weight Gain explode all trees
#3 MeSH descriptor Weight Loss explode all trees
#4 MeSH descriptor Body Mass Index explode all trees
#5 (overweight in All Text or (over in All Text and weight in All Text) )
#6 (adipos* in All Text or (fat in All Text and overload in All Text and syndrom* in All Text) )
#7 (overeat* in All Text or (over in All Text and eat* in All Text) )
#8 (overfeed* in All Text or (over in All Text and feed* in All Text) )
#9 (weight in All Text and (gain in All Text or chang* in All Text) )
#10 (body in All Text and mass in All Text and ind* in All Text)
#11 MeSH descriptor Waist circumference explode all trees
#12 MeSH descriptor Waist-Hip Ratio explode all trees
#13 MeSH descriptor Abdominal fat explode all trees
#14 MeSH descriptor Body fat distribution explode all trees
#15 MeSH descriptor Skinfold thickness explode all trees
#16 MeSH descriptor Overweight explode all trees
#17 ((weight in All Text near/6 cyc* in All Text) or (weight in All Text near/6 reduc* in All Text) or (weight in All Text near/6 los* in All Text) or (weight in All Text near/6 maint* in All Text) or (weight in All Text near/6 decreas* in All Text))
#18 ((weight in All Text near/6 watch* in All Text) or (weight in All Text near/6 control* in All Text) or (weight in All Text near/6 chang* in All Text) or (weight in All Text near/6 gain* in All Text) )
#19 BMI in All Text
#20 (waist-hip in All Text and ratio* in All Text)
#21 (waist in All Text and circumferenc* in All Text)
#22 (body in All Text and (fat in All Text near/6 distribution* in All Text) )
#23 ((abominal in All Text and fat in All Text) or (skinfold in All Text and thickness in All Text) )
#24 (obes* in All Text or adipos* in All Text)
#25 (#1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11 or #12)
#26 (#13 or #14 or #15 or #16 or #17 or #18 or #19 or #20 or #21 or #22 or #23 or #24)
#27 (#25 or #26)
#28 MeSH descriptor Diet explode all trees
#29 MeSH descriptor Dietary supplements explode all trees
#30 MeSH descriptor Caloric restriction explode all trees
#31 MeSH descriptor Directive counseling explode all trees
#32 (food in All Text near/3 formulated in All Text)
#33 (diet in All Text near/3 supplement* in All Text)
#34 (weight in All Text and (loss in All Text near/6 program* in All Text) )
#35 (weight in All Text and (loss in All Text near/6 product* in All Text) )
#36 (weight in All Text and (loss in All Text near/6 method* in All Text) )
#37 (weight in All Text and (loss in All Text near/6 book* in All Text) )
#38 (weight in All Text and (loss in All Text near/6 website* in All Text) )
#39 (weight in All Text and (loss in All Text near/6 CD* in All Text))
#40 (weight in All Text and (loss in All Text near/6 service* in All Text))
#41 (weight in All Text and (reduction in All Text near/6 program* in All Text) )
#42 (weight in All Text and (reduction in All Text near/6 method* in All Text) )
#43 (weight in All Text and (reduction in All Text near/6 book* in All Text) )
#44 (weight in All Text and (reduction in All Text near/6 website* in All Text) )
#45 (weight in All Text and (reduction in All Text near/6 CD* in All Text) )
#46 (weight in All Text and (reduction in All Text near/6 product* in All Text) )
#47 (weight in All Text and (reduction in All Text near/6 service* in All Text) )
#48 ((caloric in All Text and restriction* in All Text) or (directive in All Text and counsel* in All Text) or (food in All Text and formulated in All Text) )
#49 ((food in All Text and plan* in All Text) or (slim in All Text and fast in All Text) or (slimming in All Text and world in All Text) or (weight in All Text and watchers in All Text) or Atkins in All Text)
#50 (#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)
#51 MeSH descriptor Commerce explode all trees
#52 commerc* in All Text
#53 (#51 or #52)
#54 (#27 and #50 and #53)
MEDLINE
1 exp Diet/
2 exp Dietary supplements/
3 exp Caloric restriction/
4 exp Directive counseling/
5 exp Food formulated/
6 diet supplement*.ti,ab.
7 ((weight-loss or weight reduction) adj6 (program* or product* or method* or book* or website* or magazine* or DVD* or CD* or service* or self-help)).ti,ab.
8 (caloric restriction* or hypocaloric or very low calorie* low calorie* or VLCD* or directive counsel* or food formulated or liquid-supplement* or meal replacement*).ti,ab.
9 (food plan* or slim fast or slimming world or weight watchers or Atkins).ti,ab.
10 exp Commerce/
11 (commerc* or proprietary).ti,ab.
12 or/1-11
13 exp Obesity/ or exp Obesity hypoventilation syndrome/ or exp Obesity, abdominal/ or exp Obesity, morbid/ or exp Prader-Willi Syndrome
14 exp Overweight
15 exp Adipose tissue/
16 exp Weight gain/ or exp Weight loss/
17 exp body fat distribution/ or exp body mass index/ or exp waist circumference/ or exp skinfold thickness/ or exp waist-hip ratio/
18 exp Body Composition/
19 (overweight$ or over weight$).ti,ab.
20 fat overload syndrom$.ti,ab.
21 (overeat$ or over eat$).ti,ab.
22 (overfeed$ or over feed$).ti,ab.
23 (adipos$ or obes$).ti,ab.
24 (weight adj3 (cyc$ or reduc$ or los$ or maint$ or decreas$ or watch$ or control$ or gain$ or chang$)).ti,ab.
25 (body mass ind$ or waist-hip ratio$).ti,ab.
26 skinfold thickness$.ti,ab.
27 abdominal fat$.ti,ab.
28 ((abdominal or subcutaneous or intra-abdominal or visceral or retroperitoneal or retro peritoneal) adj3 fat*).ti,ab.
29 or/13-28
30 (clinical control* or randomi?ed control* or control*).pt.
31 controlled clinical trial.pt.
32 randomi?ed.ab.
33 placebo.ab.
34 drug therapy.fs.
35 randomly.ab.
36 trial.ab.
37 groups.ab.
38 or/30-37
39 Meta-analysis.pt.
40 exp Technology Assessment, Biomedical/
41 exp Meta-analysis/
42 exp Meta-analysis as topic/
43 hta.ti,ab.
44 (health technology adj6 assessment$).ti,ab.
45 (meta analy$ or metaanaly$ or meta?analy$).ti,ab.
46 (search$ adj10 (literature$ or medical database$ or medline or pubmed or embase or cochrane or cinahl or psycinfo or psyclit or healthstar or biosis or current content$ or systemat$)).ti,ab.
47 or/39-46
48 38 or 47
49 (comment or editorial or historical-article).pt.
50 48 not 49
51 12 and 29 and 50
52 (animals not (animals and humans)).sh.
53 51 not 52
EMBASE
1 exp diet/
2 exp diet supplementation/
3 exp caloric restriction/
4 exp directive counseling/
5 exp elemental diet/
6 diet supplement*.tw,ot.
7 ((weight-loss or weight reduction) adj6 (program* or product* or method* or book* or website* or magazine* or DVD* or CD* or service* or self-help)).ti,ab.
8 (caloric restriction* VLCD or very low calorie* or low calorie* or directive counsel* or food formulated or meal replacement* or liquid supplement*).ti,ab.
9 (food plan* or slim fast or slimming world or weight watchers or Atkins).ti,ab.
10 or/1-9
11 exp Obesity/
12 exp weight change/ or exp weight control/ or exp weight gain/ or exp weight reduction/
13 exp body mass/ or exp waist circumference/ or exp waist hip ratio/
14 exp abdominal fat/ or exp body fat distribution/
15 exp skinfold thickness/
16 (obes$ or adipos* or overweight or over weight).ti,ab.
17 (overeat or over eat or overfeed or over feed or fat overload syndrom$).ti,ab.
18 (weight adj6 (cyc$ or reduc$ or los$ or maint$ or decreas$ or watch$ or control or chang$ or gain)).ti,ab.
19 (body mass ind$ or waist hip ratio or waist circumferenc$).ti,ab.
20 (body fat adj3 distribution*).ti,ab.
21 (abdominal fat or skinfold thickness).ti,ab.
22 or/11-21
23 exp commercial phenomena/
24 commerc*.tw,ot.
25 23 or 24
26 exp Randomized Controlled Trial/
27 exp Controlled Clinical Trial/
28 exp Clinical Trial/
29 exp Comparative Study/
30 exp Drug comparison/
31 exp Randomization/
32 exp Crossover procedure/
33 exp Double blind procedure/
34 exp Single blind procedure/
35 exp Placebo/
36 exp Prospective Study/
37 ((clinical or control$ or comparativ$ or placebo$ or prospectiv$ or randomi?ed) adj3 (trial$ or stud$)).ab,ti.
38 (random$ adj6 (allocat$ or assign$ or basis or order$)).ab,ti.
39 ((singl$ or doubl$ or trebl$ or tripl$) adj6 (blind$ or mask$)).ab,ti.
40 (cross over or crossover).ab,ti.
41 or/26-40
42 exp meta analysis/
43 (metaanaly$ or meta analy$ or meta?analy$).ab,ti,ot.
44 ((review$ or search$) adj10 (literature$ or medical database$ or medline or pubmed or embase or cochrane or cinahl or psycinfo or psyclit or healthstar or biosis or current content$ or systematic$)).ab,ti,ot.
45 exp Literature/
46 exp Biomedical Technology Assessment/
47 hta.tw,ot.
48 (health technology adj6 assessment$).tw,ot.
49 or/42-48
50 41 or 49
51 (comment or editorial or historical-article).pt.
52 50 not 51
53 10 and 22 and 25 and 52
54 limit 53 to human
PsycINFO
1.  (MM "Diet*")
2.  (MM "Dietary Supplements") OR (MM "Dietary Supplementation") OR "liquid supplement*" OR "meal replacement*" OR "hypocaloric" OR "very low calorie" OR "VLCD" or "low calorie"
3.  (MM "Food")
4.  TX diet supplement*
5.  TX (weight-loss or weight reduction) n6 (program* or product* or method* or book* or website* or magazine* or DVD* or CD* or service*)
6.  TX caloric restriction* or directive counsel* or food formulated
7.  TX food plan* or slim fast or slimming world or weight watchers or Atkins or ("self-help")
8.  commerc* or ("proprietary")
9.   S1 or S2 or S3 or S4 or S5 or S6 or S7 OR S8
10. (MM "Obesity")
11. (MM "Adipose Tissue")
12. (MM "Body Weight Changes")
13. (MM "Weight Control")
14. (MM "Body Mass Index")
15. MM ("Waist Circumference") OR (MM "Waist-Hip Ratio")
16. (MM "Skinfold Thickness")
17. (MM "Abdominal Fat")
18. (MM "Body Composition")
19. TX overeat or "over eat" or overfeed or "over feed" or "fat overload syndrom*"
20. TX adipos* or obes*
21. TX overweight* or "over weight*"
22. TX weight n6 cyc* or reduc* or los* or maint* or decreas* or watch* or control or chang* or gain
23. TX "body mass ind*" or "waist-hip ratio*" or "waist circumference"
24. TX "abdominal fat*" or "skinfold thickness*"
25. TX "body fat" n3 distribution*
26. S10 or 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
27. (MM "Clinical Trials")
28. (MM "Comparative Studies") OR (MM "Prospective Studies")
29. (MM "Crossover Design")
30. (MM "Crossover Design") Search modes - SmartText Searching
31. (MM "Placebo")
32. TX (clinical or control* or comparativ* or placebo* or prospectiv* or randomi*) n3 (trial* or stud*)
33. TX random* n6 (allocat* or assign* or basis or order*)
34. TX (singl* or doubl* or trebl* or tripl*) n6 (blind* or mask*)
35. TX crossover or "cross over"
36. S27 or S28 or S29 or S30 or S31 or S32 or S33 or S34 or s35
37. (MM "Meta Analysis")
38. "metaanaly*" or "meta analy*" or "meta?analy*"
39.  TX (review* or search*) n10 (literature* or "medical database*" or medline or pubmed or embase or cochrane or cinahl or psycinfo or psyclit or healthstar or biosis or "current content*" or systematic*)
40.  (MM "Literature Searching")
41.  "health technology" n6 assessment*
42.  TX hta
43.  S37 or S38 or S39 or S40 or S41 or S42
44.  PT comment or editorial or historical-article
45.  (S36 OR S43) NOT S44
46.  S9 and S26 and S45
47.  Limiters - Population Group: Human
CINAHL
1.    (MH "Diet+")
2.    (MH "Dietary Supplements+") OR (MH "Dietary Supplementation") OR "liquid supplement*" OR "meal replacement*" OR "very low calorie" or VLCD" or low calorie" or "hypocaloric"
3.    (MH "Food, Formulated+")
4.    TX diet supplement*
5.    TX (weight-loss or weight reduction) n6 (program* or product* or method* or book* or website* or magazine* or DVD* or CD* or service*)
6.    TX caloric restriction* or directive counsel* or food formulated
7.    TX food plan* or slim fast or slimming world or weight watchers or Atkins or ("self-help")
8.    TX commerc* or ("proprietary")
9.    S1 or S2 or S3 or S4 or S5 or S6 or S7 or S8
10.  (MH "Obesity+")
11.  (MH "Adipose Tissue+")
12.  (MH "Body Weight Changes+")
13.  (MH "Weight Control")
14.  (MH "Body Mass Index")
15.  MH ("Waist Circumference") OR (MH "Waist-Hip Ratio")
16.  (MH "Skinfold Thickness")
17.  (MH "Abdominal Fat")
18.  (MH "Body Composition")
19.  TX overeat or "over eat" or overfeed or "over feed" or "fat overload syndrom*"
20.  TX adipos* or obes*
21.  TX overweight* or "over weight*"
22.  TX weight n6 cyc* or reduc* or los* or maint* or decreas* or watch* or control or chang* or gain
23.  TX "body mass ind*" or "waist-hip ratio*" or "waist circumference"
24.  TX "abdominal fat*" or "skinfold thickness*"
25.  TX "body fat" n3 distribution*
26.  S10 or 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
27.  (MH "Clinical Trials+")
28.  (MH "Comparative Studies") OR (MH "Prospective Studies+")
29.  (MH "Crossover Design")
30.  (MH "Placebos")
31.  TX (clinical or control* or comparativ* or placebo* or prospectiv* or randomi*) n3 (trial* or stud*)
32.  TX random* n6 (allocat* or assign* or basis or order*)
33.  TX (singl* or doubl* or trebl* or tripl*) n6 (blind* or mask*)
34.  TX crossover or "cross over"
35.  S27 or S28 or S29 or S30 or S31 or S32 or S33 or S34
36.  (MH "Meta Analysis")
37.  TX "metaanaly*" or "meta analy*" or "meta?analy*"
38.  TX (review* or search*) n10 (literature* or "medical database*" or medline or pubmed or embase or cochrane or cinahl or psycinfo or psyclit or healthstar or biosis or "current content*" or systematic*)
39.  (MH "Literature Searching+")
40.  TX "health technology" n6 assessment*
41.  TX hta
42.  S36 or S37 or S38 or S39 or S40 or S41
43.  PT comment or editorial or historical-article
44.  (S35 OR S42) NOT S43
45.  S9 AND S26 AND S26 AND S44
46.  Limiters Human 
'My NCBI' alert service
commercial[All Fields] AND ("weight reduction programs"[MeSH Terms] OR ("weight"[All Fields] AND "reduction"[All Fields] AND "programs"[All Fields]) OR "weight reduction programs"[All Fields] OR ("weight"[All Fields] AND "loss"[All Fields] AND "programs"[All Fields]) OR "weight loss programs"[All Fields])

Appendix 2. Description of interventions

Characteristic

Study ID

Intervention(s) [route, frequency, total dose/day]Comparator(s) [route, frequency, total dose/day]
Study 1Intervention 1Comparator 1
 Intervention 2Comparator 2

Footnotes

"-" denotes not reported

Appendix 3. Baseline characteristics (I)

CharacteristicIntervention(s) and comparator(s)Duration of intervention (duration of follow-up)Participating populationStudy period [year to year]CountrySettingEthnic groups [%]Duration of condition [mean/range years (SD), or as reported]
Study 1Intervention 1       
 Intervention 2       
 Comparator 1       
 Comparator 2       
      all:  

Footnotes

"-" denotes not reported

SD: standard deviation

Appendix 4. Baseline characteristics (II)

CharacteristicIntervention(s) and comparator(s)Sex [female %]Age [mean/range years (SD), or as reported]BMI [mean kg/m2 (SD)]Co-medications / Co-interventionsCo-morbidities
Study 1Intervention 1     
 Intervention 2     
 Comparator 1     
 Comparator 2     
 all:     

Footnotes

"-" denotes not reported

BMI: body mass index; SD: standard deviation

Appendix 5. Matrix of study endpoints (publications)

Characteristic Endpoint reported in publicationEndpoint not reported in publicationTime of measurementa
Example Review's primary outcomes
Adverse effects x0, 12 mo
Health-related quality of lifex  0, 6, 12 mo
Weight change and change in body mass index (BMI)x 0, 12 mo
Review's secondary outcomes
Attritionx  0, 12 mo
Change data for percentage overweight and obese, waist-to-hip ratio, waist circumference, cholesterol (total cholesterol, HDL-cholesterol, LDL-cholesterol), blood pressure (diastolic and systolic)x  0, 6, 12 mo
Compliance with commercial weight loss product or service xN/A
Morbidity xN/A
Mortality, all-cause xN/A
Other than review's primary/secondary outcomes reported in publication (classification: P/S/O)b
Insulin resistance (P), patient satisfaction (S), safety parameters (O), socioeconomic outcomes (O)
Subgroups reported in publication
Age < 65 years vs. ≥ 65 years, obesity vs overweight

Footnotes

aUnderlined data denote times of measurement for primary and secondary review outcomes, if measured and reported in the results section of the publication (other times represent planned but not reported points in time).

b(P) Primary or (S) secondary endpoint(s) refer to verbatim statements in the publication, (O) other endpoints relate to outcomes which were not specified as 'primary' or 'secondary' outcomes in the publication.

BMI: body mass index; HDL: high-density lipoprotein; LDL: low-density lipoprotein; mo: months; N/A: not acknowledged

Appendix 6. Matrix of study endpoints (trial documents)

Characteristic / Study ID (trial identifier)Endpointa Review's primary outcome Review's secondary outcomeTime of measurementSource (FDA document / EMA document / manufacturer's website / design paper / trial protocol document)
E x a m p l eCardiovascular mortality (P) x12 mo 
Health-related quality of life (O)x 24 mo
Myocardial infarction (S) x6, 12 mo

Footnotes

"-" denotes not reported

a(P) Primary or (S) secondary endpoint(s) refer to verbatim statements in the publication, (O) other endpoints relate to outcomes which were not specified as 'primary' or 'secondary' outcomes in the report

mo: months; N/A: not acknowledged

Appendix 7. Examination of outcome reporting bias

CharacteristicClear that outcome was measured and analyseda [trial report states that outcome was analysed but only reports that result was not significant]Clear that outcome was measured and analysedb [trial report states that outcome was analysed but no results reported]Clear that outcome was measuredc [clear that outcome was measured but not necessarily analysed (judgement says likely to have been analysed but not reported because of non-significant results)]Unclear whether the outcome was measuredd [not mentioned but clinical judgement says likely to have been measured and analysed but not reported on the basis of non-significant results]
Study 1    

Footnotes

'High risk of bias' categories for outcome reporting bias according to the Outcome Reporting Bias In Trials (ORBIT) study classification system for missing or incomplete outcome reporting in reports of randomised trials (Kirkham 2010).

aClassification 'A' (table 2, Kirkham 2010)

bClassification 'D' (table 2, Kirkham 2010)

cClassification 'E' (table 2, Kirkham 2010)

dClassification 'G' (table 2, Kirkham 2010)

Appendix 8. Definition of endpoint measurement (I)

Characteristic

Study ID

Health-related quality of lifeAttritionOverweightObesityWaist-to-hip ratioWaist circumference
Study 1      

Footnotes

ND: not defined; N/I: not investigated

Appendix 9. Definition of endpoint measurement (II)

Characteristic

Study ID

CostsComplianceMorbiditySevere / serious
adverse events
Study 1    

Footnotes

ND: not defined; N/I: not investigated

Appendix 10. Adverse events (I)

Characteristic

Study ID

Intervention(s) and
comparator(s)
Randomised /
Safety
[N]
Deaths
[N]
Deaths
[%]
All adverse
events
[N]
All adverse
events
[%]
Severe/serious
adverse events
[N]
Severe/serious
adverse events
[%]
Study 1Intervention 1       
Intervention 2       
Comparator 1       
Comparator 2       
  all:       

Footnotes

"-" denotes not reported

Appendix 11. Adverse events (II)

Characteristic

Study ID

Intervention(s) and
comparator(s)
Randomised / Safety
[N]
Left study due to adverse events
[N]
Left study due to adverse events
[%]
Hospitalisation
[N]
Hospitalisation
[%]
Out-patient treatment
[N]
Out-patient treatment
[%]
Study 1Intervention 1       
Intervention 2       
Comparator 1       
Comparator 2       
  all:       

Footnotes

"-" denotes not reported

Appendix 12. Adverse events (III)

Characteristic

Study ID

Intervention(s) and
comparator(s)
Randomised / Safety
[N]
Specific adverse events
[description]
Specific adverse events
[N]
Specific adverse events
[%]
Study 1Intervention 1    
Intervention 2    
Comparator 1    
Comparator 2    
  all:    

Footnotes

"-" denotes not reported

 

Appendix 13. Survey of authors providing information on included trials

Characteristic

Study ID

Study author contactedStudy author repliedStudy author asked for
additional information
Study author provided data
Study 1Y   

Footnotes

N: no; Y: yes

Contributions of authors

Alisha M Crayton (AC): protocol draft, search strategy development, acquirement of trial copies, trial selection, data extraction, data analysis, data interpretation, review draft and future review updates.

Carolyn D Summerbell (CS): protocol draft, search strategy development, acquirement of trial copies, trial selection, data extraction, data analysis, data interpretation, review draft and future review updates.

Tance J Sonnier (TS) : protocol draft, search strategy development, review draft and future review updates.

Louisa J Ells (LE): protocol draft, search strategy development, review draft and future review updates.

Harry R Rutter (HR): protocol draft, search strategy development, review draft and future review updates.

Frank K Greenway (FG): protocol draft, search strategy development, review draft and future review updates.

Declarations of interest

Alisha M Crayton: none known.

Carolyn D Summerbell: none known.

Tance J Sonnier: none known.

Louisa J Ells: none known.

Harry R Rutter: none known.

Frank K Greenway: I consult for a number of companies involved in the obesity space. I hold several patents in the obesity space. I am a member of several advisory boards in the obesity space including the head of the Medical Advisory Board for Jenny Craig which is a commercial weight loss program. I hold stock in four companies in the obesity space.

Note from the Metabolic and Endocrine Disorders Group: according to the 'Cochrane organisational, editorial and publishing policies' (http://www.cochrane.org/about-us/our-policies/cochrane-policies) authors with a direct financial interest in a particular intervention will not be involved in a Cochrane Review of that intervention.

Sources of support

Internal sources

  • Durham University, UK.

    This review is one element of study is funded by Durham University, as part of a PhD researching commercial weight loss products and services.

External sources

  • No sources of support supplied

Ancillary