The Effectiveness and Safety of a Mobile Application Based Self-Regulation Intervention to Support Weight Loss Among Adults Living with Obesity: A Randomised Controlled Trial

Abstract

Background: Obesity is a leading risk factor for avoidable ill health. Effective interventions that can be delivered at scale are needed to support people living with excess weight to lose weight.

Methods: We conducted a two-arm randomised controlled trial among adults aged ≥18 years living with obesity. Participants were recruited via online social media advertisements and allocated 1:1 to receive access to a purpose-built mobile application based on self-regulation theory or advice to lose weight. Co-primary outcomes were change in weight and the proportion of participants achieving ≥5% weight loss at six months. We also assessed whether the intervention had adverse effects on symptoms of disordered eating. Analyses were performed intention-to-treat, and per-protocol, using linear mixed effects and analogous logistic models. The trial was registered on clinicaltrials.gov: NCT05787652.

Findings: From 13 April to 15 May 2023, 1,607 participants were randomly assigned to control (n=806), or intervention (n=801). Weight was reported by 632 (39·3%) participants at six months. Mean difference in weight change between groups at six months in intention-to-treat analyses was -1·85kg (95% CI: -2·53, -1·17, p<0·001), and the odds of losing ≥5% were 2·11 (95% CI: 1·48, 3·03, p<0·001). Per-protocol analyses showed participants using the app lost an additional -2·18kg compared to control, and the odds of losing ≥5% were 2·44 (95% CI: 1·67, 3·59, p<0·001). The proportion of participants scoring above threshold for symptoms of disordered eating declined in intervention relative to control at six months (adjusted OR: 0·51, 95% CI: 0·29, 0·91, p=0·024).

Interpretation: An app with no human contact, designed to foster self-regulatory behaviours, increased weight loss and reduced symptoms of disordered eating in people living with obesity and could be safely deployed at population-level to support effective weight management.

Trial Registration: The trial was registered on clinicaltrials.gov: NCT05787652.

Funding: Oxford and Thames Valley Applied Research Collaboration (ARC).

Declaration of Interest: GW is supported by a Medical Research Council (MRC) industrial collaborative award in science and engineering (iCASE) studentship in which the commercial partner is Second Nature, but they had no involvement in this trial or paper. PA and SAJ are investigators on two publicly funded clinical trials in which Nestle donated total diet replacement products to support NHS treatment costs.

Ethical Approval: The trial was approved by the Central University Research Ethics Committee of the University of Oxford (R82050/RE001). After reading the PIS, potential participants were provided a link to the study website where they could consent to participate.

Keywords: Digital health, obesity, self-regulation, weight loss