Effectiveness of a self-regulation intervention for weight loss: A randomized controlled trial

To evaluate effectiveness and acceptability of a novel intervention, based on self-regulation theory, for weight loss.

A two-arm parallel group design was employed.

Adult participants with a BMI ≥ 30 kg/m² and the aim to lose weight were recruited and randomized to either a control or intervention group. Both groups were asked to weigh themselves daily for eight weeks. The intervention group was encouraged to use a weight tracking app, and complete daily and weekly questionnaires to prompt action planning, reflection, and evaluation of actions. Participants chose daily actions from a menu of 53 behaviours. The primary outcome was weight change after 8 weeks, assessed using linear mixed effects models. At follow-up, 20 intervention group participants were interviewed regarding their experiences in the trial.

100 participants were recruited, and 98% were followed up at 8 weeks. Mean weight loss was -4.18 kg (SD = 3.84) in the intervention compared to -1.01 kg (SD = 2.67) in the control group; the adjusted difference was -3.20 kg (95% CI -4.49, -1.92). Participants rated the intervention's usefulness as 8.25 (SD = 2.04) on a scale from 1 to 10. Adherence was a significant independent predictor of weight loss success (-1.54 kg per one SD, 95% CI -2.16, -0.93), but not a mediator of the intervention effect. Participants reported that the intervention enabled them to experiment with and identify effective weight loss actions.

Guiding participants through the self-regulation process was feasible, acceptable to participants, and led to significantly greater short-term weight loss than unguided self-weighing.