Comment on: Extending weight loss programs pays dividends
Weight loss is difficult for people with obesity, but many people are only offered short term support or advice only; although the UK National Institute for Health and Care Excellence obesity guideline is based on evidence for trials of at least 12 months duration, in the UK National Health Service many programs are only of 12 weeks duration, on the basis that the evidence base is weak for longer treatment courses. The WRAP study recruited people with obesity from UK primary care and randomized them to a control of leaflet and advice only, or to a 12 week or 52 week group-based intervention (provided by Weight Watchers UK, who partially funded the research). Weight loss was greatest for those people who attended the 52 week program, intermediate for those who attended the 12 week program and least for those who were given advice only. It is interesting that the weight loss and proportion achieving 5% weight loss was greater than in many published studies and this may reflect patient self-selection and a strong “trial effect” as even the minimal intervention group lost a significant amount of weight. As expected, risk factors such as glycated hemoglobin and blood pressure improved to a greater extent with longer treatment duration, and this translates into tangible benefits in a cost-effectiveness analysis that shows all three interventions would be considered cost-effective, mainly on the basis of reducing diabetes and hypertension; this was greatest for the 52 week intervention.
These data are important and reinforce previous research findings suggesting that duration of the intervention and contact time can influence outcomes in weight management. This is particularly relevant for programs to prevent diabetes, such as the National Diabetes Prevention Programme in the UK, and for services that are offering weight loss support in primary care. Longer duration programs of 52 weeks are more clinically effective than shorter programs, and also cost-effective so it is hoped that it might improve provision of support for weight loss in primary care. It is telling that only 1% of randomized patients had previously received lifestyle support for weight loss from their general practitioner, reflecting the current extremely low levels of support for weight management within primary care in the UK.
It is important not to extrapolate these data beyond the population studied. Those included had an average body mass index (BMI) of around 35 kg/m2, 13% had diabetes and half were hypertensive. We are not given data on the proportion who had other significant obesity related comorbidities such as prediabetes, obstructive sleep apnea, or heart disease, and those with eating disorders, severe psychiatric illness or learning difficulty were excluded. By contrast, patients attending specialist weight management services and those considering bariatric surgery would be expected to have a BMI in excess of 40 kg/m2, most with multiple comorbidities such as diabetes and sleep apnea, a high proportion of psychological comorbidity, and many previous unsuccessful attempts at weight loss. This group is likely to need more specialist support than can be provided by the commercially provided group-based behavioral intervention described in this paper.