Weight management programmes of extended duration

www.thelancet.com Published online May 3, 2017 http://dx.doi.org/10.1016/S0140-6736(17)31042-5 1 In 2014, 52% of adults globally were overweight or obese. Lifestyle programmes, which target improved diet and exercise practices, reliably produce clinically relevant weight changes and are viable options that can reach multiple populations and be delivered on a large scale. Consequently, these lifestyle programmes remain a popular approach to weight management despite better long-term weight loss outcomes being observed using different methods. Amy Ahern and colleagues empirically assessed the effects of extended access to a group-based, commercial weight loss programme (Weight Watchers). Their large, randomised controlled trial (n=1267 patients) compared the effects on weight loss (alongside other clinical outcomes) of a brief intervention with 12-week and 52-week programme referrals (free access). The investigators used primary care providers to recruit adults who were overweight or obese across England. Both referral groups referred to the commercial programme showed better weight loss outcomes than the brief intervention group, which received only self-help materials from their doctor. Mean weight loss in participants given a 52-week referral was 6·76 kg at 12 months and 4·29 kg at 24 months, which represented 2·14 kg and 1·32 kg greater weight loss compared with the 12-week referral group at these same timepoints (when adjusted for baseline values and centre). Although modest, these differences are relevant within the pragmatic objectives of the study— ie, to understand whether extended access to a weight management programme could improve weight loss in a real-world setting. Furthermore, the accompanying economic analysis dispels cost-prohibitive arguments about extended programme access and greatly strengthens the proposal that 52-week referrals to a commercial programme might be a worthwhile alternative to the 12-week referrals currently supported by the National Health Service (NHS) in the UK. The finding that prolonged access to interventions can improve weight outcomes might seem obvious at first; if participants have extended access to active support, they continue to lose weight. However, sparse empirical studies have attempted to quantify the effects of active intervention duration on weight loss outcomes. The widely used 12-week duration for academic study of weight loss programmes and in commercial offerings has no clear clinical basis and it is a challenge to find substantiating empirical studies. Some studies have explored specific aspects of interventions, such as frequency and style of participant contact, which might overlap with intervention duration. Few studies, if any, have sought to directly test the effects of different intervention durations. The comparison of different intervention lengths creates some methodological challenges. For example, data collected at follow-up visits represent different lengths of inactive intervention within each participant group. Despite some criticism, pragmatic trials are an excellent method for overcoming such challenges and informing current practice. Beyond this applied focus, the results presented by Ahern and colleagues suggest that prolonged access to active intervention might offer a simple and cost-effective method for improving weight loss outcomes in lifestyle intervention programmes. This is an important finding because higher initial weight loss can improve long-term success of weight management. Prolonged active intervention could increase weight loss simply by delaying the onset of weight regain, which is considered stable and unrelated to initial weight loss or programme characteristics. However, could extended treatment duration be used to mitigate the substantial challenge of weight regain? Weight monitoring, accountability, and different Weight management programmes of extended duration