Testing Just-in-Time Adaptive Interventions (JITAIs) to Prevent Goal Disengagement in Response to Weight Regain

This trial will test the effectiveness of a weight loss maintenance intervention designed to help participants respond more adaptively to weight regain. Participants will be randomly assigned to one of two conditions. In one condition, participants will receive brief exercises (e.g., written reflections, videos) sent to through a smartphone app immediately after they regain weight or miss a weigh-in. These exercises will use mindfulness, acceptance, and self-compassion strategies to help participants stay motivated for their long term goals, even when weight regain feels demoralizing. In the comparison condition, participants will receive weekly reminders of standard weight control strategies strategies.

Inclusion Criteria: * Ages 18-70 years * BMI of 25-50 kg/m2 * Current weight is 3% lower than their highest weight in the past 3 years * Desire to maintain their weight or lose more * Ability to engage in PA, as defined as being able to walk two full city blocks without stopping * Smartphone and Internet access * Successful completion of all enrollment procedures * Ability to attend a workshop(s) on a Monday or Tuesday evening Exclusion Criteria: * History of bariatric surgery * History of being diagnosed with an eating disorder * Currently pregnant, breastfeeding, or planning to become pregnant in the next 24 months * Enrolled in another formal weight loss/weight maintenance program * Currently taking a GLP-1 medication.