Behavioural interventions for preventing and treating obesity in adults


Associate Professor M Sharma, Health Promotion and Education, University of Cincinnati, 526 Teachers College, PO Box 210002, Cincinnati, OH 45221-0002, USA. E-mail:


The purpose of this study was to review existing behavioural interventions for preventing and treating obesity in adult population that were published between 2000 and September 2006. A total of 23 interventions were found. Most of these interventions targeted both physical activity and nutrition behaviours. Majority of the interventions were not based on any explicit behavioural theory. In terms of duration, the interventions ranged from 3 weeks to 9 years. Approximately half of the interventions were less than 6 months in duration. Most of the interventions were implemented by the researchers themselves. However, some interventions were implemented by nurse educators, nutritionists, trained public health nurses, dietitians, healthcare providers, fitness workers and certified diabetic educators. Most of the interventions used group sessions as the predominant method to deliver the programme. Three of the interventions used media. Majority of the interventions were implemented in patient care settings with some in community settings. The most common determinant for measuring impact of the interventions has been body mass index. Fifteen interventions showed positive change in adiposity indices while six showed no change in adiposity indices. Recommendations for enhancing the effectiveness of behavioural interventions for prevention of obesity are presented.


Overweight and obesity are major causes of morbidity and mortality in the United States and most industrialized countries of the world. In the United States, the prevalence of obesity has been increasing since 1980s (1). In 2003–2004, based on National Health and Nutrition Examination Survey, the prevalence of overweight [BMI (body mass index) ≥25 kg m−2] in adults was found to be 66.3% and of which 32.2% were found to be obese (BMI ≥ 30 kg m−2) (2). This was an increase from 1999 to 2000 when overweight was found to be 64.5% and obesity was found to be 30.5% (3). Based on the Behavioural Risk Factor Surveillance System, a random digit telephone survey conducted in all states in 2000, with 184 450 adults over 18 years, it was found that the prevalence of obesity (BMI ≥ 30 kg m−2) was 19.8% (4).

Similarly in the United Kingdom in 2003, 60% of women and 68% of men were overweight or obese (5). In Germany, 70% men and 50% women were found to be obese (6). In Spain, prevalence of obesity has been found to be 14.5% in one study (7) and 13% in another study (8). A 1994 analysis in Denmark showed the prevalence of obesity to be 12% in men and 11% in women (9). In a study in Iceland, the prevalence of obesity was found to be 19% (10). In a study in Poland, in 2003 it was found that 15% women and 6.5% men were obese (11). In 2003, in Canada, 15.2% individuals were found be obese (12). A study in South Australia found that obesity rates (BMI ≥ 30–<35) increased significantly from 8.7% in 1991 to 14.1% in 2003 (P < 0.001) and severe obesity (BMI ≥ 35) increased significantly from 2.6% in 1991 to 5.3% in 2003 (P < 0.001) (13). In a study in Turkey, the prevalence of obesity was found to be 35% (14). A study carried out in Saudi Arabia found overweight (BMI = 25–29.9) to be 36.9% and obesity (BMI ≥ 30) to be 35.5% (15).

In the United States, it is estimated that approximately 300 000 deaths annually are attributed to obesity-related conditions (16). The economic burden of adult obesity is estimated to be as high as 100 billion per year (17). In 1995, about 5% of the national healthcare budget was spent on the direct costs of obesity and its consequent diseases (18).

Determinants of overweight and obesity

Overweight and obesity are caused by various factors. Body weight is shaped by a combination of genetic, metabolic, behavioural, environmental, cultural and socio-economic influences. Overweight and obesity can be examined from an individual level clinical perspective or an environmental public health perspective (19). In the individual level clinical perspective, obesity occurs because of individual level variations in variables such as efficiency of thermogenesis, substrate utilization and biologic set points. In the public health perspective, obesity occurs because of differing levels of exposure to causative agents in different populations that comprise of decreasing levels of energy expenditure and increasing caloric intake especially from fats. Decreasing levels of energy expenditure usually occur from decreasing leisure-time physical activity, increasing television viewing, computers, videos, labour-saving devices, unsafe neighbourhoods, reduced physical education programming in schools, increased automobile use and decreased use of public transportation. Therefore, for a large majority of individuals, overweight and obesity result from excess calorie consumption and/or inadequate physical activity (20). According to the US Department of Agriculture’s 1994–1996 Continuing Survey of Food Intakes by Individuals, very few Americans meet the majority of the Food Guide Pyramid recommendations (21). Only 3% of all individuals meet four of the five recommendations for the intake of grains, fruits, vegetables, dairy products and meats. Further, less than one-third of adults engage in the recommended amount of physical activity, and 40% of adults engage in no leisure-time physical activity (22). Interventions that modify factors for obesity can be for prevention or treatment. Preventive interventions are implemented with unselected population that may be normal weight or obese with a goal of prevention of weight gain. Treatment interventions are implemented with overweight or obese individuals with a goal of weight loss. Interventions for prevention and treatment of obesity can be behavioural, pharmacological, surgical or environmental. Schmitz and Jeffery note that the public health efforts to prevent obesity have focused mainly on individual education and behavioural skills training (19). Commonly suggested educationally modifiable public health strategies to combat childhood obesity are promoting breastfeeding, limiting television viewing, increasing physical activity, increasing fruit and vegetable intake, controlling portion size, and limiting soft drink consumption (23).


It is in this backdrop that the aims of this study were to review behavioural interventions for prevention and treatment in adult population that were published between 2000 and September 2006 and suggest ways of enhancing these interventions. It was decided to focus on interventions that had an educational component. In order to restrict the number of studies from becoming overwhelming, it was decided to focus on recent studies starting from the year 2000. This is a narrative review and not a quantitative meta-analysis.


In order to collect the materials for the study, a search of MEDLINE database was carried out for the time period 2000–September 2006. The criteria for inclusion of the studies were (i) publication in English language; (ii) publication between 2000 and September 2006 (included were studies conducted prior to 2000 that were published in the specified time period); (iii) location of study anywhere in the world; (iv) focus on adult population and (v) having an explicit educational approach for prevention and control of obesity. Exclusion criteria were publications in languages other than English, publications prior to 1999 and studies that focused on pharmacological or surgical approaches to overweight and obesity.


The interventions that are discussed in this article are summarized in Table 1. These have been arranged according to the year of publication. A total of 23 studies met the inclusion criteria. Of these 12 interventions were from the United States, two each from Australia and Netherlands, and one each from Belgium, Canada, Finland, Japan, Italy, Sweden and the United Kingdom.

Table 1.  Summary of interventions for preventing and controlling obesity in adults
Study/year/country/focusTheoryInterventionDurationMajor findings
  1. BMI, body mass index; HDL, high-density lipoprotein.

Metz et al. (24)/ 2000/United States/treatmentNo known behavioural theoryOverweight and obese (BMI ≥ 25 and ≤42) individuals (n = 302) with hypertension/dyslipidemia or type 2 diabetes mellitus were randomly assigned to prepared meal plan or usual care diet (UCD) for 52 weeks. The prepared meal plan was formulated to provide recommended levels of sodium, fat, fibre and was fortified to meet 100% of recommended dietary allowance for 22 essential vitamins and minerals.52 weeksIn the prepared meal plan group, the average weight loss from baseline was 6.9 ± 4.0 kg, 7.8 ± 6.3 kg after 26 weeks and 5.8 ± 6.8 kg after 52 weeks as compared with UCD group losing 2.3 ± 3.6 kg after 12 weeks, 2.4 ± 5.4 kg after 26 weeks and 1.7 ± 6.5 kg after 52 weeks. The difference between two groups was significant (P < 0.001). In both groups, both interventions improved blood pressure, total and low-density lipoproteins (LDLs), cholesterol, glycosylated haemoglobin and quality of life.
Looma healthy lifestyle programme (25)/2000/Australia/ preventionNo known behavioural theoryFormal and informal education sessions, regular physical activity groups, dietary changes such as cutting fat from meat before cooking, reducing intake of refined carbohydrate (sugars and carbonated beverages), and increasing consumption of fruits and vegetables. Cooking classes and store tours.Physical activity promotion through hunting trips, participation in sport, and regular walking groups.2 yearsMean BMI in intervention group decreased significantly at 6 months when compared with non-intervention group (P = 0.01) but was not significant after 12 months. At 2-year follow-up, there were fewer persons reporting no attempts to lower their intake of fat and/or sugar (χ2 = 42.0, P < 0.001). At 2-year follow-up, the proportion of sedentary individuals also decreased (χ2 = 4.0, P = 0.046).
Fogelholm et al. (26)/2000/Finland/ treatmentNo known behavioural theory85 overweight premenopausal women were recruited. There were three phases (i) 12 weeks’ weight reduction phase with very low energy diet; (ii) maintenance phase where participants were randomized into three groups for 40 weeks: control, walking group targeted to expend 4.2 MJ week−1, walking group targeted to expend 8.4 MJ week−1; (iii) unsupervised 2-year follow-up phase.3 yearsMean weight loss after the 12-week programme was 13.1 kg. During the maintenance phase, the mean body weight increased by 2.0 kg in the control group while in the walking group 1 the weight change was −2.7 kg and walking group 2 was −2.6 kg (P = 0.06). At the end of the follow-up, the mean weight increased in all three groups. However, walking group 1 had gained 3.5 kg less weight than control.
Women’s Healthy Lifestyle Project (27)/2001/United States/ preventionCognitive behavioural approachParticipants were randomly assigned into control group (n = 275) and lifestyle intervention group (n = 260). Aimed at increasing leisure-time physical activity, preventing weight gain and preventing the increase of LDL cholesterol. Restrict dietary fat to 25%. Intensive group programme during the first 6 months and follow-up individual/group sessions from 6 to 54 months.5 yearsIn the lifestyle intervention group, the weight change at 6 months was −10.7 lb (P < 0.01), at 18 months −6.7 lb (P < 0.01), at 30 months −4.7 lb (P < 0.01), at 42 months −2.2 lb (P < 0.01) and at 54 months −0.18 lb (P < 0.01).Corresponding significant reductions were also found in waist circumference as compared with control group.
Himeno et al. (28)/ 2001/Japan/ treatmentNo known behavioural theoryExercise training for 1 h thrice a week at a heart rate corresponding to anaerobic threshold on a cycle ergometer or walking on a treadmill (n = 23). Personal counselling to restrict diet to a caloric intake less than 1000 kcal per day from standard caloric intake was implemented.12 weeksBMI decreased from 31 ± 3.7 kg m−2 to 29.3 ± 3.6 kg m−2 (P < 0.0001). Body fat decreased from 29.9 ± 3.2% to 27.0 ± 3.5% (P < 0.0001). Waist/hip ratio decreased from 0.94 ± 0.06 to 0.91 ± 0.06 (P < 0.0001).
Jakicic et al. (29)/ 2002/United States/treatmentNo known behavioural theoryThree groups (i) long bouts of exercise; (ii) short bouts of exercise; (iii) short bouts of exercise combined with home exercise equipment.Focused on modifying both eating (reducing fat intake to 20–30% of total calorie intake which was between 1200 and 1500 kcal d−1 using structured meal plans) and exercise behaviours (maintain exercise to 200 min per week). Group meetings were scheduled weekly for months 1–6, biweekly for months 7–12 and monthly for months 13–18.18 monthsThe mean decrease in weight from baseline to 18 months was −7.8 ± 7.5 kg (P < 0.001). The mean decrease in BMI from baseline to 18 months was −2.8 ± 2.7 kg m−2 (P < 0.001).The mean increase in physical activity from baseline to 18 months was 1146 ± 1300 kcal week−1 (P < 0.001). The mean reduction in energy intake from baseline to 18 months was −498.1 ± 783.7 kcal d−1 (P < 0.001). The mean reduction in fat intake from baseline to 18 months was −27.4 ± 38.4 g d−1 (P < 0.001).
Diet, Exercise, and Weight Loss Trial (DEW-IT) (30)/ 2002/United States/treatmentNo known behavioural theoryLifestyle intervention group (n = 22) and control group (n = 23). Lifestyle group required DASH (Dietary Approach to Stop Hypertension) diet, reduced sodium, weight loss goal of 10 pounds or 1.25 pounds per week for 8 weeks and exercise for 30–45 min.9 weeksFrom baseline to follow-up BMI decreased by −1.9 kg m−2 in lifestyle group and was significant when compared with control group (P < 0.0001). From baseline to follow-up weight decreased by −5.5 kg in lifestyle group and was significant when compared with control group (P < 0.0001).
Steps to Soulful Living (Steps) (31)/2002/United States/ treatmentSocial support26 weekly group meetings and a weekly supervised exercise class (n = 66, African–American women). Dietary goal was to reduce fat intake to 25% of total energy and exercise goal was to exercise three to four times a week for 30 min or more.Intervention had five key elements (i) increasing identification between counsellors and participants; (ii) building social support; (iii) providing information in a demonstration format; (iv), involving family and community; (v) increasing programme ownership.26 weeksOver the 26 weeks, women lost a mean of 3.7 ± 5.1 kg or a mean loss of 3.3% of their body weight. 56% of the participants lost 2.4 kg (5 lb) or more. Participants who attended at least 75% of the group meetings lost a mean of 6.2 kg at 6 months and those who attended fewer meetings lost a mean of 0.9 kg.
Burke et al. (32)/ 2002/Australia/ treatmentSocial cognitive theoryCouples were randomized to three groups: usual care control group (n = 43), low-level intervention (n = 47) and high-level intervention (n = 47). Intervention aimed at 30-min physical activity on most days and a diet with <30% energy as fat was implemented as workshop sessions and mail out information.4 monthsIn the control group, 5% increase in overweight individuals occurred at post- intervention which increased to 11% after 1 year and in low-level intervention group it was 2% and at 1 year 9% while in high- level intervention there was no change in the proportion of overweight individuals. No significant between-group differences in BMI were found.
Tate et al. (33)/ 2003/United States/treatmentNo known behavioural theoryOne group (n = 46) received Internet- based tutorial on weight loss, anew tip and link each week, and directory of weight loss resources.Second group (n = 46) in addition received behavioural e-counselling and interacted with counsellors via e-mail about calorie and fat intake, and exercise energy expenditure.1 yearBehavioural e-counselling group had greater reduction in weight (−4.4 vs. −2.0 kg, P = 0.04), BMI (−1.6 vs. −0.8 kg m−2, P = 0.03) and waist circumference (−7.2 vs. −4.4 cm, P = 0.05) when compared with Internet group. Both groups reported significant reductions in caloric intake between 0 and 12 months (P < 0.001). For both groups, mean increase in exercise energy expenditure did not differ from 0 to 12 months (P = 0.26).
Hearts for Life (34)/ 2003/Canada/ preventionNo known behavioural theoryMedia was involved with launching of the programme. 1016 participants participated in the project. Programme content addressed heart disease, risk factors, risk reduction strategies delivered by public health nurses using verbal presentation. Video on healthy eating was also included.3 months46.2% of the population had BMI > 27. The mean score on knowledge test was 7.47 at pre-test which increased to 8.26 at post-test (P < 0.001) and at 3-month follow-up was 8.17.Of those participants who were initially overweight (BMI > 27), 78% reported improving their weight, 81.7% reported improving their nutrition and 67.3% reported increasing their exercise.
Lantz et al. (35)/ 2003/Sweden/ treatmentNo known behavioural theoryA total of 334 patients with BMI > 30 kg m−2 were randomly assigned to very-low-calorie diet (VLCD) in an on demand group (60 completers) and an intermittent group (57 completers). For 16 weeks, all participants were given VLCD. Then intermittent group used VLCD for 2 weeks every third month while on-demand group used VLCD whenever their weight passed an individualized cut-off level.All subjects were recommended hypocaloric diet during VLCD-free period.2 yearsAt the end of 2 years, both groups had significant weight loss but between groups there was no difference. In the intermittent group the weight loss was 7.0 ± 11.0 kg (6.2 ± 9.5%) while in on-demand group the weight loss was 9.1 ± 9.7 kg (7.7 ± 8.1%). Most cardiovascular risk factors also improved.
Pounds off with empowerment (POWER) (36)/ 2004/United States/treatmentGoal settingThree interventions based on a goal of achieving 10% weight loss over 12 months: intensive lifestyle intervention, reimbursable lifestyle intervention and usual care.Intensive lifestyle intervention included group sessions led by nutritionists, written materials, encouragement and suggestions for physical activity at low to moderate intensity for sedentary people, dietary modifications, self-monitoring tools. Reimbursable lifestyle intervention was condensed and included four 1-h sessions over 12 months and three group sessions and one individual session. Usual care included one individual session by a nutritionist.12 monthsWeight change at 6 months was significantly greater among intensive lifestyle participants compared with usual care participants (2.6 kg vs. 0.4 kg, P < 0.01). At 12 months, greater proportion of intensive lifestyle participants had lost 2 kg or more than usual care participants (49% vs. 25%, P < 0.05). No change in weight was observed between reimbursable lifestyle and usual care participants.
Read et al. (37)/ 2004/United Kingdom/ treatmentNo known behavioural theorySeven 2-h education and support group sessions were organized by dietitian at intervals of 2 weeks (total 12 weeks). In addition, 2-h topical sessions were held at 4 months, 6 months, 9 months and 12 months. No control group was used.12 monthsAt 3 months, mean weight decrease was 3.1 kg (P < 0.0001), BMI decrease was 1.1 (P < 0.0001) and waist circumference decrease was 4.9 cm (P < 0.0001). However, at 12 months weight, BMI and waist circumference showed no change.
Fat and Activity Tailored to Health (FAITH)project (38)/2005/Belgium/ preventionTheory of planned behaviour and transtheoretical modelTwo interactive computer-tailored interventions targeting increasing physical activity and decreasing fat intake were implemented.Participants were randomly assigned to receive (i) physical activity and fat intake interventions simultaneously; (ii) physical activity intervention at baseline and fat intake intervention after 3 months; (iii) fat intake intervention at baseline and physical activity intervention at 3 months; (iv) control group.6 monthsTailored interventions at 6 months produced significantly higher physical activity scores (F(2,573) = 11.4, P < 0.001) and lower fat intake scores (F(2,565) = 31.4, P < 0.001) in the experimental groups when compared with the control group. Both sequential and simultaneous interventions were found to be effective. Adiposity indices not measured.
Maffiuletti et al. (39)/2005/Italy/ treatmentNo known behavioural theoryImplemented with 70 obese volunteers. Combination of energy-restricted diet (1200–1800 kcal d−1), nutritional education (consisting of lectures, demonstrations, group discussions for 60 min every day), psychological counselling (2–3 times week−1 for 60 min), moderate physical activity (five sessions per week of 10 min on ergocycle, 20 min on treadmill and 5 min on arm-ergometer).3 weeks with follow-up at 1 yearBMI at pre-test was 41.3 ± 4.3, which was significantly reduced to 39.3 ± 3.9 (P < 0.001) at post-test and was further reduced to 38.8 ± 4.9 (P < 0.001). Fat mass (kg) at pre-test was 53.7 ± 10.5, which was significantly reduced to 50.0 ± 10.3 (P < 0.001) at post-test and was further reduced to 48.0 ± 12.1 (P < 0.001). Success rate in females (n = 37/45, 82%) was higher than in males (n = 11/19, 57.9%). At follow-up, weight losers had higher percent fat-free mass, higher muscle strength, higher HDL cholesterol, higher self- reported physical activity level, lower total cholesterol and lower glucose levels.
Kennedy et al. (40)/ 2005/United States/treatmentNo known behavioural theoryTwo treatment groups: group intervention (n = 20) and individual intervention (n = 20).Group intervention: nutrition education in six monthly group meetings using group discussion. Individual intervention: 15 individualized meetings, record keeping, basic dietary assessment using computer software.6 monthsMean weight loss in all participants at 6 months was 3.3 kg (SD 3.5, P < 0.05). In group-based intervention mean weight loss was 3.1 kg (SD 3.5, P < 0.05) while in individual intervention it was 3.4 kg (SD 3.5, P < 0.05).Mean BMI decrease in all participants was 1.2 kg m−2 (SD 1.3, P < 0.05). In group-based intervention it was −1 (SD 1) while in individual intervention it was −1.3 (SD 1.3, P < 0.05).
Physician based assessment and counselling for exercise (PACE) (41)/2005/ Netherlands/treatmentTranstheoretical model and social cognitive theoryModified from American PACE programme developed in 1990s. Two visits with the provider and two booster calls from a counsellor. First visit stage assessment form filled out and stage-specific guidance was given. Counsellor telephoned after 2 weeks. Follow-up was planned with provider at 4 weeks. Final booster telephone call after 8 weeks.8 weeks, follow-up at 1 yearNo statistically significant intervention effects were noted for weight or BMI over the study period. Statistically inverse intervention effect over time was observed for waist circumference which increased (P < 0.001). PACE intervention was no more effective than the standard physical activity advice.
Finch et al. (42)/ 2005/United States/treatmentOutcome expectations theoryTwo groups: one group received positive or optimistic outcome expectations and the other group received balanced outcome expectations (both positive and negative). Eight weekly, 1-h group sessions involving presentation by facilitator and a group discussion. First four sessions influenced expectations about losing weight. Second four sessions were designed to implement self-designed weight loss plan.8 weeks, follow-up at 18 monthsNo significant differences in weight change by treatment group were observed at 8 weeks, F(3,212) = 0.70, P < 0.40; 6 months, F(3,201) = 0.01, P < 0.93; or 18 months, F(3,181) = 0.18, P < 0.67. Positive outcome expectations and satisfaction were found to be associated with weight loss.
Wammes et al. (43)/ 2005/ Netherlands/ preventionSocial marketing theoryMass media campaign. Components (i) radio advertising (4 weeks); (ii) brochure with BMI self-test and a tape measure to measure waist circumference; (iii) advertisements in daily newspapers and popular glossy magazines; (iv) distribution of free cards; (v) website and a call centre.2 monthsAfter the campaign, about 65% respondents knew about the campaign. Campaign was associated with more positive attitudes towards prevention of weight gain (β = 0.16, P < 0.01) and higher self-reported BMI (β = 0.14, P < 0.01). Changes in adiposity indices not measured.
Cherokee Choices (44)/2006/United States/ preventionSocial marketing theoryComponents: worksite wellness for adults, church-based health promotion, and social marketing using TV documentary series, and TV advertisements. Worksite wellness programme (n = 86) and church wellness programme had healthy cooking demonstrations, classes on exercise techniques and supermarket tours.3 years88% completed the worksite wellness programme and 56% met the goals. 70.9% lost weight (29.1% <5 lb, 12.8% 5–<10 lb, 20.9% 10–<20 lb, 8.1%≥20 lb). In 86 participants, 0.85 kg m−2 change in BMI between June 2002 and June 2005.
Women’s Health Initiative Dietary Modification Trial (45)/2006/United States/treatmentNo known behavioural theoryGroups of 8–15 participants underwent a series of sessions to promote dietary and behavioural changes to reduce dietary fat to 20% and increase consumption to ≥5 fruits and vegetables. Eighteen sessions in first 12 months, after that four per year. Additionally three individual interviews that used targeted messages and provided personalized feedback. The control group received diet-related education materials.9 yearsWomen in the intervention group lost weight in the first year (mean of 2.2 kg, P < 0.001) and maintained lower weight than control women during an average 7.5 years of follow-up (difference, 1.9 kg, P < 0.001 at 1 year and 0.4 kg, P = 0.01 at 7.5 years). Weight loss was greatest in women who reduced their percentage of energy from fat.
Hypertension, Overweight/obesity, lipidemia, diabetes, smoking, stress (HOLDSS) (46)/ 2006/United States/treatmentTranstheoretical model and social cognitive theoryPatient-centred personal risk counselling based on stage of change. Stage of change was assessed at each visit and intervention accordingly tailored.Measurements at baseline, 6 weeks, 3 months, 6 months.6 monthsAt 6 weeks the mean body weight change from baseline was 2.7 lb as compared with 0.6 lb in control group (P < 0.01), at 3 months the mean body weight change from baseline was 5.2 lb as compared with 1.3 lb in control group (P < 0.001), at 6 months the mean body weight change from baseline was 5.6 lb as compared with 0.9 lb in control group (P < 0.01). Changes in behaviour and its antecedents not measured.


The purpose of this study was to review existing behavioural interventions for prevention and treatment of obesity in adult population that were published between 2000 and September 2006 and suggest ways of enhancing these interventions. Six interventions (25,27,34,38,43,44) can be classified as preventive interventions that were implemented with unselected population with a goal of prevention of weight gain while 17 interventions were treatment interventions implemented with overweight or obese individuals with a goal of weight loss. Most of these interventions (n = 18) targeted both physical activity and nutrition behaviours. Four interventions targeted only nutrition behaviours (1,34,35,37) and one targeted only physical activity behaviour (41). Interventions targeting both physical activity and nutrition behaviours were more successful in influencing adiposity indices.

Most of the interventions (n = 13) were not based on any explicit behavioural theory. Three interventions used two theories. In the 10 interventions that did use a theory, the theories that were used included social cognitive theory (n = 3) (32,41,46), transtheoretical model (n = 3) (38,41,46), social marketing theory (n = 2) (43,44), cognitive behavioural approach (n = 1) (27), theory of planned behaviour (n = 1) (38), social support (n = 1) (31), construct of goal setting (n = 1) (36) and construct of outcome expectations (n = 1) (42). Use of a theory helps in discerning which components work and which components do not work. However, except for one intervention, the interventions that have used behavioural theories have not measured changes in constructs that predict behaviour. Such measurement is important as it helps in identifying salient constructs and increasing predictive potential as well as improving the theory. Researchers and evaluators must make effort to develop psychometrically robust instruments that measure the changes in constructs of the theory that is being used in the intervention.

In terms of duration, the interventions have ranged from 3 weeks to 9 years. Approximately half of the interventions (n = 12) have been less than 6 months in duration. Four interventions have been 1 year long, one for 18 months and six have been 2 years or more in length. Figure 1 depicts the variation in duration of the interventions.

Figure 1.

Duration of obesity prevention and treatment interventions.

Interventions shorter than 6 months have higher failure rate as compared with longer interventions. Future intervention planners must make efforts to design interventions that are at least 6 months long. Further, generally speaking, interventions that have not used a behavioural theory have been more than a year long. If behavioural theories are reified adequately, the time of the interventions can be reduced and more meaningful interventions can be designed that are shorter than a year in duration.

Most of the interventions were implemented by the researchers themselves. However, some interventions were implemented by nurse educators (25), nutritionists (26,44), trained public health nurses (34), dietitians (37,44), healthcare providers (general practitioners and nurse practitioners) (41), fitness workers (44) and certified diabetic educators (46). It is surprising to note that despite the fact that all of these interventions were educational in nature, only two interventions were implemented by trained educators. This finding coupled with the fact that most of the interventions did not utilize a behavioural theory warrants that future interventions must not only utilize behavioural theories but also use trained educators. The quality of implementation of educational sessions would improve considerably if trained educators are used. Furthermore, researchers should design interventions that can be easily replicated by trained health professionals for these to be generalized. More efforts should be taken to develop such interventions.

Most of the interventions used group sessions as the predominant method to deliver the programme. However, eight interventions utilized one-on-one counselling (31,33,36,39,40,41,45,46). From these eight interventions, one utilized electronic counselling (33) and one utilized telephone counselling (41) while the rest used conventional one-on-one counselling. All of the interventions that used conventional one-on-one counselling and electronic counselling produced successful results. This indicates that one-on-one counselling as an educational tool needs to be utilized by future interventions.

Three of the interventions used media (34,43,44) in dissemination of the messages for weight loss. Media was used in launching of the programme (34), radio advertisements (43), advertisement in newspapers and magazines (43), television advertisements (44), and television documentaries (44). As this component was mixed with other approaches, it is not clear to what extent media contributed to overall success of the intervention. Involvement of media is often associated with expenses and all interventions may not be able to afford the expenses. Nonetheless, media is a useful adjunct to any weight loss intervention and must be utilized where ever feasible.

Majority of the interventions have been implemented in patient care or hospital settings. However, nine interventions have been implemented in community settings (25,31,34,36,38,40,42,43,45) and one in worksite setting (44). The setting does not seem to be related to success or failure of the intervention. Interventions in both settings have been successful. However, there have been fewer interventions in community and worksite settings and more such interventions need to be planned.

All the interventions have focused on individual level behaviour change. Only one intervention (24) has focused on creating supportive environments by way of giving participants monetary compensation for health food purchase and one has built social support (31). There is need for educational programmes to be supported by environmental and policy changes that support the behaviour change. More interventions should look at influencing policies and environments along with education.

The most common determinant for measuring impact of the interventions has been BMI. Weight, waist circumference and body fat have also been used by interventions. Two interventions (38,43) have measured other antecedents and not measured changes in adiposity indices. Fifteen interventions have showed positive change in adiposity indices while six (25,32,37,41,42) have showed no change in adiposity indices. With many interventions, while statistical significance was achieved, the results were not practically significant as the person who started out by being overweight was still overweight although he or she may have lost weight. Interventions targeting both physical activity and nutrition behaviours were more successful in influencing adiposity indices.

Recommendations for enhancing educational obesity prevention and treatment interventions

Obesity prevention and treatment interventions must focus on both physical activity and nutrition behaviours. In nutrition behaviours aspects for increased fruit and vegetable consumption, decreased fat intake, decreased consumption of carbonated drinks, adequate consumption of water and restricting portion sizes are important aspects.

There is need for all interventions to be based on behavioural theories. Besides reifying theories, it is also mandatory for interventions to develop instruments that measure constructs of behavioural theories. Use of behavioural theories helps in understanding which components work and to what extent helps in timing the interventions, and makes professional communication easier.

In terms of setting, more interventions should target community and worksite settings where early stages of obesity can be detected and programmatic efforts initiated in a timely manner. For advanced stages of obesity, interventions carried out in patient care settings are also useful.

In terms of the duration of the intervention, interventions that are at least 6 months long must be planned. Trained educators must be used in delivery of the educational interventions. Where ever possible one-on-one counselling should be used as an educational approach. This counselling can be delivered electronically, if face-to-face interaction is not possible. Likewise, if media can be involved through newspaper advertisements, radio advertisements or television spots, it must be carried out. For intervention activities, there is need to support individuals to make behaviour changes in their diets and exercise habits. At the same time, there is a need to change both policies and environments so that these are supportive of entire communities in eating healthy foods and enjoying regular physical activity. Hence, educational programmes need to be supplemented with health promotion interventions that change policies and environments.

Conflict of Interest Statement

No conflict of interest was declared.