Commercial weight-loss programmes: are they effective for people with type 2 diabetes?

Weight loss is advocated as a primary therapy for the 90% of people with type 2 diabetes who are overweight or obese, but the capacity of the NHS to provide an integrated, cost-effective weight management service limits application. It has been reported that conventional weight loss services within the NHS are less effective than group-based commercial interventions including Rosemary Conley, Slimming World and WeightWatchers. These commercial organisations now offer weight management services in many areas of the UK through slimming on referral. There is evidence from randomised controlled trials and from audit demonstrating the efficacy of commercial groups for people without diabetes, but little evidence for those with diabetes. The aim of this review is to explore the evidence for these commercial providers in people with diabetes. Both Slimming World and WeightWatchers, but not Rosemary Conley, have published evidence of efficacy in their general groups. Only Slimming World has audited those with type 2 diabetes but this was a small, self-reported study. Independent head-to-head trials and audit data from those without diabetes suggest that commercial programmes are effective for weight loss. Extrapolating these data to those with type 2 diabetes suggests that there is little to choose between the main commercial providers, that individuals can expect to lose 3-5kg over 12 weeks, and that attrition rates over 12 months or less are approximately 40-60%. Commercial groups are probably effective for those with diabetes, but there is little published evidence available about the effects on weight loss, glycaemic control and attrition rates. Copyright (C) 2015 John Wiley & Sons.