This project aims to evaluate a newly developed Internet-delivered (via e-learning modules) acceptance-based behavioral intervention (ABTi) for individuals who are experiencing weight regain after bariatric surgery. Specifically, the investigators aim to assess ABTi's efficacy on stopping and/or reversing weight by comparing it to a wait-list control (WLC) condition. The investigators also aim to evaluate its effect on targeted weight control behaviors and acceptance-based skills. Finally, the investigators will examine the relationship between weight outcomes and changes in process variables through exploratory analyses. Treatment outcomes (i.e., weight, maladaptive behaviors, physical activity, acceptance-based skills) will be measured at assessments pre-, mid-, and post-treatment, as well as at 3 months after treatment has ended.

Primary Aims.

1. To test the hypothesis that participants randomly assigned to ABTi will display greater weight loss from pre- to post-treatment than those assigned to WLC.
2. To test the hypothesis those receiving ABTi, compared to WLC, will display decreased maladaptive eating behaviors (i.e., loss of control episodes, grazing, emotional eating, disinhibition), increased physical activity, and greater improvements in acceptance-based skills (i.e., mindfulness, defusion, food-related acceptance).

Exploratory Aim.

(1) To assess if changes in acceptance-based skills, maladaptive eating behaviors, and physical activity are associated with pre- to post-treatment weight outcomes.

Inclusion Criteria:

• Has undergone any type of weight loss surgery at least 1.5 years ago
• Demonstrate ≥ 10% weight regain of maximum weight loss or 5% of their minimum weight post-surgery, with weight regain lasting for at least 3 months prior to enrollment.
• Ability to give consent and speak, write, and understand English.

Exclusion Criteria:

• Currently enrolled in structured weight loss program
• Currently pregnant/plan to become pregnant within 6 months of enrollment
• Have a serious medical condition that has the potential of affecting weight or that would prevent engagement in dietary changes and/or an exercise regimen
• Exhibit psychiatric symptoms that would interfere with the ability to benefit from the intervention, or report acute suicidality
• Non-ambulatory (i.e., unable to walk at least one city block without a cane or walker at the time of screening
• Use of medications known to affect body weight, such as chronic systemic steroids or psychiatric medications including lithium, tricyclic antidepressants, and antipsychotic agents