Primary care referral to a commercial provider for weight loss treatment versus standard care: a randomised controlled trial

Background: The increasing prevalence of overweight and obesity needs effective approaches for weight loss in primary care and community settings. We compared weight loss with standard treatment in primary care with that achieved after referral by the primary care team to a commercial provider in the community.

Methods: In this parallel group, non-blinded, randomised controlled trial, 772 overweight and obese adults were recruited by primary care practices in Australia, Germany, and the UK. Participants were randomly assigned with a computer-generated simple randomisation sequence to receive either 12 months of standard care as defined by national treatment guidelines, or 12 months of free membership to a commercial programme (Weight Watchers), and followed up for 12 months. The primary outcome was weight change over 12 months. Analysis was by intention to treat (last observation carried forward [LOCF] and baseline observation carried forward [BOCF]) and in the population who completed the 12-month assessment. This trial is registered, number ISRCTN85485463.

Findings: 377 participants were assigned to the commercial programme, of whom 230 (61%) completed the 12-month assessment; and 395 were assigned to standard care, of whom 214 (54%) completed the 12-month assessment. In all analyses, participants in the commercial programme group lost twice as much weight as did those in the standard care group. Mean weight change at 12 months was -5·06 kg (SE 0·31) for those in the commercial programme versus -2·25 kg (0·21) for those receiving standard care (adjusted difference -2·77 kg, 95% CI -3·50 to -2·03) with LOCF; -4·06 kg (0·31) versus -1·77 kg (0·19; adjusted difference -2·29 kg, -2·99 to -1·58) with BOCF; and -6·65 kg (0·43) versus -3·26 kg (0·33; adjusted difference -3·16 kg, -4·23 to -2·11) for those who completed the 12-month assessment. Participants reported no adverse events related to trial participation.

Interpretation: Referral by a primary health-care professional to a commercial weight loss programme that provides regular weighing, advice about diet and physical activity, motivation, and group support can offer a clinically useful early intervention for weight management in overweight and obese people that can be delivered at large scale.

Funding: Weight Watchers International, through a grant to the UK Medical Research Council.