Evaluating the efficacy of mindfulness and acceptance-based treatment components for weight loss: Protocol for a multiphase optimization strategy trial.

Behavioral weight loss treatment (BT) for individuals with overweight and obesity is effective but leaves room for improvement. Mindfulness and acceptance-based treatments may bolster weight loss outcomes; yet, little is known about the efficacy of the individual components or the combinations of components that are most effective in producing weight loss above and beyond standard BT strategies for weight loss. This protocol manuscript describes the use of a multiphase optimization strategy to evaluate the independent and combinatory efficacy of three mindfulness and acceptance-based components (mindful awareness, willingness, values). Using a 2 × 2 × 2 factorial design, participants (N = 288) will be randomized to one of eight conditions, each representing a combination of core MABT strategies in addition to foundational BT strategies. Assessments occur at baseline, mid-treatment (week 24 through 26), post-treatment, and at 6, 12, and 24-month follow-up. The primary aim is to elucidate the independent efficacy of each MABT component on weight loss above gold-standard BT. The secondary aims are to evaluate the independent effect of these components on calorie intake, physical activity, and overall quality of life; evaluate target engagement (i.e., the degree to which each treatment component affects proposed mechanisms of action); and evaluate the potential moderating effect of susceptibility to internal and external food cues on outcomes. The exploratory aim is to quantify any component interaction effects (which may be synergistic, fully additive, or partially additive).