Study protocol for a randomized controlled trial comparing two low-intensity weight loss maintenance interventions...

Weight regain is common following behavioral obesity treatment and attenuates many of the benefits of initial weight loss. This paper describes a randomized controlled trial that will evaluate the efficacy of two low-contact weight loss maintenance interventions based on Acceptance and Commitment Therapy (ACT) and self-regulation (SR). Potential mechanisms of action and moderators of treatment effects will also be evaluated.

Adults (anticipated N = 480) with overweight or obesity will complete an initial 3-month online weight loss program (Phase 1). Participants who achieve ≥4 kg weight loss (anticipated N = 288) will then be randomized to an ACT or SR weight loss maintenance intervention. Both interventions will entail four 2.5 h, face-to-face, group-based workshop sessions and 6 months of email contact. Assessments will be conducted at phase 1 baseline, phase 1 completion/pre-randomization, and 6, 12, 18, 24, and 30 months post-randomization. The primary outcome will be weight change for the period from randomization to 30 months. Potential process measures including ACT-based constructs (e.g., psychological acceptance, values-consistent behavior), self-weighing frequency, and motivation will be also be assessed, as will potential moderators (e.g., initial weight loss).

This study will compare the efficacy of two intervention approaches (ACT and SR) delivered in a scalable workshop format for long-term weight loss maintenance. Future research could examine efficacy and cost-effectiveness of these approaches in real world settings.