Objective To evaluate the efficacy, as well as potential moderators and mediators, of a revised acceptance-based behavioral treatment (ABT) for obesity, relative to standard behavioral treatment (SBT). Design and Methods Participants with overweight and obesity (n=190) were randomized to 25 sessions of ABT or SBT over 1 year. Primary outcome (weight), mediator and moderator measurements were taken at baseline, 6 months and/or 12 months, and weight was also measured every session. Results Participants assigned to ABT attained a significantly greater 12-month weight loss (13.3% ± 0.83) than did those assigned to SBT (9.8% ± 0.87; p=.005). A condition by quadratic time effect on session-by-session weights (p=.01) indicated that SBT had a shallower trajectory of weight loss followed by an upward deflection. ABT participants were also more likely to maintain a 10% weight loss at 12 months (64.0% vs 48.9%; p=.04). No evidence of moderation was found. Results supported the mediating role of autonomous motivation and psychological acceptance of food-related urges. Conclusion Behavioral weight loss outcomes can be improved by integrating self-regulation skills that are reflected in acceptance-based treatment, i.e., tolerating discomfort and reduction in pleasure, enacting commitment to valued behavior, and being mindfully aware during moments of decision making.

Background Adherence to dietary prescriptions is critical for successful weight loss and weight loss maintenance. However, research on specific instances of inadherence (lapses) is limited, and findings regarding the frequency, nature and causes of lapses are mixed. Additionally, no studies have examined lapses over the course of a weight loss program. Purpose In the context of a reduced calorie diet prescribed as part of a behavioral treatment, we aimed to characterize lapse occurrence, examine lapse frequency across treatment, examine predictors of lapses, and assess the relationship between lapses and weight loss. Methods Adults (n = 189) enrolled in a 12-month behavioral weight loss program completed ecological momentary assessment (EMA) at baseline, mid-treatment, and end-of-treatment. At each EMA survey, participants indicated whether a lapse had occurred, and responded to questions assessing situational, environmental, and affective states. Results Lapse frequency showed a curvilinear relationship over time, such that frequency first decreased and then increased. More frequent lapses at baseline were associated with less early and overall weight loss. Lapses occurred most often at home, in the evenings, on the weekends, and entailed eating a forbidden food. Greater overall levels of assessed affective and environmental triggers predicted lapses; greater momentary hunger and deprivation, and the presence of palatable food also prospectively predicted lapses. Conclusions In addition to characterizing lapse frequency, the current study identified prospective predictors of lapses across treatment. These findings support the importance of lapses to weight control, and provide insight for potential targets of intervention to prevent lapse occurrence.

This pilot study provides initial support for the feasibility, acceptability, and preliminary efficacy of a remotely delivered acceptance-based behavioral intervention for postoperative weight regain.

This randomized trial demonstrated qualified support for the ability of a machine learning-powered, smartphone-based just-in-time, adaptive intervention to enhance weight loss over and above a commercial weight loss program.

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