Testing the short‐term effectiveness of primary care referral to online weight loss programmes:A randomised controlled trial

Guidelines ask health professionals to offer brief advice to encourage weight loss for people living with obesity. We tested whether referral to one of three online programmes could lead to successful weight loss. A total of 528 participants aged ≥18 years with a body mass index of ≥30 kg/m2 were invited via a letter from their GP. Participants were randomised to one of three online weight loss programmes (NHS Weight Loss Plan, Rosemary Online or Slimming World Online) or to a control group receiving no intervention. Participants self-reported weight at baseline and 8 weeks. The primary outcome was weight change in each of the active intervention groups compared with control. We also compared the proportion of participants losing ≥5% or ≥10% of body weight. For Rosemary, Online mean weight loss was modestly greater than control (-1.5 kg [95% confidence interval (CI) -2.3 to -0.6]) and more than three times as many participants in this group lost ≥5% (relative risk [RR] = 3.64, 95% CI: 1.63–8.1). For Slimming World, mean weight loss was not significantly different from control (-0.8 kg [95%CI -1.7 to 0.1]), twice as many participants lost ≥5% (RR = 2.70, 1.17–6.23). There was no significant difference in weight loss for participants using the NHS Weight Loss Plan (-0.4 kg, [95% CI -1.3 to 0.5]), or the proportion losing ≥5% (RR = 2.09, 0.87–5.01). Only one of three online weight loss programmes was superior to no intervention and the effect size modest among participants living with obesity.What is already known about this subject?• Until recently face to face group-based programmes have been the mainstay of weight management services, but there has been a rapid rise in the availability of digital interventions, further accelerated by the COVID-19 pandemic.• Systematic review evidence shows that digital interventions result in effective weight loss but there is considerable heterogeneity which may arise either because of differences in intervention components or participant characteristics.• Little is known about the effectiveness of referrals to digital interventions with little or no in-person contact.What this study adds?• This study shows that referral to the tested online weight loss programmes is, at best, only marginally superior to no intervention.• Low or no weight loss in the intervention groups emphasises the need to carefully monitor the outcomes of programmes to encourage continual improvement.• Low uptake to the intervention should prompt caution in using letters to recruit participants to weight loss interventions in routine care