This is a plain English summary of an original research article
The evidence is growing that group-based weight loss programmes can offer effective and acceptable options for overweight people, particularly men. On average, people in group dietary advice and exercise programmes lose 3.5kg more than non-participants by six months – a modest 4% weight loss overall but less than the 5% that is often regarded as clinically important.
In this systematic review on the group weight loss approach, participants in the 47 trials were adults from the general population, taking part in groups of at least three people, led by a facilitator. The interventions varied considerably in setting, contact time, group size, facilitators’ background and intervention content.
This wide variation and reporting limitations mean that it is difficult to determine exactly what works and how. The group approach seems generally effective, more so for men than women, and is more effective in those programmes that target weight loss rather than maintenance.
Why was this study needed?
Obesity is a major public health concern across the UK and internationally. In 2016, 26% of men and 27% of women in England were obese, and a further 40% of men and 30% of women were overweight.
People who are overweight or obese have a much greater risk of developing type 2 diabetes, heart disease and stroke, joint problems and some cancers.
The risks associated with obesity can be substantially reduced with as little as 5% of body weight loss. Group lifestyle approaches to weight loss have potential to save money and offer peer support to participants, and the reviewers aimed to look at the combined interventions delivered in groups.
An existing Cochrane review looked at exercise combined with dietary change, but not specifically at a group approach. Other studies have focused on groups with pre-existing health conditions. The current review increases the evidence on the general population.
What did this study do?
This study was a systematic review of randomised controlled trials of group-based diet and physical activity interventions. It included adults from the general population who were overweight or obese (defined as BMI 25 kg/m2 or more or BMI more than 29 kg/m2 respectively).
Sixty separate group-based interventions were described in 47 trials, with 10,703 participants. Interventions involved changes in diet and physical activity combined, diet alone, or exercise behaviour alone. Interventions were delivered in a range of settings including the community (football clubs), healthcare settings (primary care practices), universities and worksites. Interventions used tools such as diaries, apps and pedometers; and education and support through printed materials, email or phone, or face to face.
The main outcome was weight-loss compared with a control group not receiving the intervention, at the follow-up points closest to 6, 12 and 24 months from baseline.
The mixed quality of included trials means that these results are unreliable and the variety of approaches limit conclusions about exactly how effective group interventions work and what the effective components might be.
What did it find?
- Overall, group-based interventions had a greater weight loss by 3.5 kg at 6 months (95% confidence interval [CI] -4.2 to ‑2.8), 3.4 kg at 12 months (95% CI -4.2 to -2.9), and 2.6 kg at 24 months (95% CI -3.8 to -1.3).
- Explicitly targeting weight loss and including feedback and diet goals/plans were signiﬁcantly associated with intervention effectiveness.
- Group-based interventions delivered to men only were on average twice as effective as those to women only (average weight 5.5 vs 2.6 kg).
- Mean attendance was 67%, as reported for 41 interventions (range 21–87%).
What does current guidance say on this issue?
In general, multicomponent lifestyle interventions, incorporating dietary, physical activity and behavioural components, are central to the recommendations of NICE guidelines and NICE public health guidance on obesity management.
NICE public health guidance from 2014 recommends that group lifestyle-based interventions are offered if an individual does not have a preference for individual attention.
What are the implications?
Group-based diet and physical activity programmes for overweight and obese people can achieve modest weight loss. Group programmes can be more beneﬁcial when they explicitly target weight loss, include separate groups for men only, and involve feedback and speciﬁc diet goals/plans. The NIHR Dissemination Centre has published a research Highlight on managing obesity in men.
Those designing programmes will need to consider the characteristics of these effective programmes and the behavioural change techniques they use. However, different group approaches seem to have broadly similar benefits and have the potential to be cheaper per head and therefore more efficient use of resources compared with individual support.
Citation and Funding
Borek AJ, Abraham C, Greaves CJ, Tarrant M. Group-based diet and physical activity weight-loss interventions: a systematic review and meta-analysis of randomised controlled trials. Appl Psychol Health Well Being. 2018;10(1):62-86.
This project was funded by the National Institute for Health Research Collaboration for Leadership in Applied Health Research and Care of the South West Peninsula (PenCLAHRC), C. Greaves’ Career Development Fellowship (CDF-2012-05-029), and A. Borek’s PhD scholarship from the University of Exeter.
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