Supporting Weight Management during COVID-19 (SWIM-C): twelve-month follow-up of a randomised controlled trial of a web-based, ACT-based, guided self-help intervention

OBJECTIVES: We developed a guided self-help intervention (Supporting Weight Management during COVID-19, "SWIM-C") to support adults with overweight or obesity in their weight management during the COVID-19 pandemic. This parallel, two-group trial (ISRCTN12107048) evaluated the effect of SWIM-C on weight and determinants of weight management over twelve months. METHODS: Adults (≥18 years, BMI ≥25 kg/m²) were randomised to SWIM-C or a standard advice group (unblinded) and completed online questionnaires at baseline, four months, and twelve months. The primary outcome was change in self-reported weight from baseline to twelve months; secondary outcomes were eating behaviour (uncontrolled eating, emotional eating, cognitive restraint), experiential avoidance, depression, anxiety, stress, wellbeing and physical activity. INTERVENTIONS: SWIM-C is based on acceptance and commitment therapy (ACT) and included 12 weekly web modules plus email and telephone support from a trained, non-specialist coach; the control received a leaflet on managing weight and mood during COVID-19. RESULTS: 388 participants were randomised (SWIM-C: n=192; standard advice: n=196). The baseline-adjusted difference in weight change between SWIM-C (n=119) and standard advice (n=147) was -0.81 kg (95% CI: -2.24 to 0.61 kg). SWIM-C led to reductions in experiential avoidance (-2.45 [10–70 scale], 95% CI: -4.75 to -0.15), uncontrolled eating (-5.52 [0–100], 95% CI: -9.67 to -1.37), emotional eating (-4.49 [0–100], 95% CI: -7.57 to -1.42) and an increase in physical activity (8.96 MET-min/week, 95% CI: 0.29 to 17.62) versus standard advice; no effects were found on other outcomes. No adverse events were reported. CONCLUSIONS: While effects on weight were inconclusive, SWIM-C improved eating behaviours, experiential avoidance and physical activity. Further refinement is needed to achieve meaningful weight effects prior to implementation.

Julia Mueller, Rebecca Richards, Rebecca A. Jones, Fiona Whittle, Jennifer Woolston, Marie Stubbings, Stephen J. Sharp, Simon J. Griffin, Jennifer Bostock, Carly A. Hughes, Andrew J. Hill, Clare E. Boothby, Amy L. Ahern