The goal of this clinical trial is to test the effectiveness of remotely-delivered interventions (utilizing acceptance-based behavioral treatment skills (ABTi)) amongst bariatric surgery populations who are experiencing weight regain postoperatively (\> 5% from their lowest postoperative weight and after postoperative Month 6). Investigators aim to evaluate ABTi's efficacy for reversing weight regain and its effect on targeted weight control behaviors and weight-related comorbidities by comparing participants randomly assigned ABTi (n = 100) to those assigned to a Control group that also receives brief phone calls but that focus on reiterating instruction on the dietary and behavioral changes required of surgery and initially taught preoperatively (C, n = 100). The main research aims are: 1. To compare changes in body weight over 12 months in 200 bariatric patients who have regained \> 5% of their weight and are randomly assigned to ABTi or Control. 2. To compare changes in eating behaviors (i.e., caloric intake, frequency of maladaptive eating behaviors), physical activity, and weight-related comorbidities (i.e., biomarkers of diabetes, hypertension) over 12 months in the two groups. 3. Exploratory - To test ABTi's theoretical mechanisms of action, including a) effects of theory-based active ingredients (i.e., acceptance, defusion, values clarity, mindfulness) on weight outcomes and b) changes in impact of internal states (i.e., hunger, cravings) on eating behavior.