Many behavioral weight loss interventions have been developed, but still have significant limitations in terms of achieving clinically significant, sustained weight loss. A recent study incorporating Acceptance and Commitment Therapy (ACT) in a randomized clinical trial resulted in participants who attained significantly greater 12-month weight loss in the ACT arm than those assigned to standard behavioral treatment, suggesting that ACT may have the potential to improve behavioral weight loss outcomes. The investigators have developed a novel telephone-delivered version of the ACT behavioral weight loss intervention, based on proven success using ACT telephone counseling intervention for smoking cessation.

There is consistent evidence from observational studies that higher amounts of body fat are associated with increased risks of cancer. Many behavioral weight loss interventions have been developed, but still have significant limitations in terms of achieving clinically significant, sustained weight loss. A recent study incorporating Acceptance and Commitment Therapy (ACT) in a randomized clinical trial resulted in participants who attained significantly greater 12-month weight loss in the ACT arm than those assigned to standard behavioral treatment, suggesting that ACT may have the potential to improve behavioral weight loss outcomes. However, this study required in-person clinic visits with treatment groups, which limits its potential reach and disseminability. The investigators have developed a novel telephone-delivered version of the ACT behavioral weight loss intervention, based on our proven success using ACT telephone counseling intervention for smoking cessation. There will be a two-arm pilot randomized trial (N = 100), comparing the ACT telephone intervention to a standard behavioral treatment (SBT) telephone control. The pilot RCT will yield engagement, receptivity, and preliminary weight loss results that will provide critical and timely weight loss intervention data.

Inclusion Criteria:

• age 18 or older,
• overweight or obese (BMI ≥ 27),
• wants to lose weight through healthy behavior change, beginning in the next 30 days,
• interested in learning skills to lose weight,
• willing to be randomly assigned to either condition,
• resides in US,
• has daily access to their own phone and email,
• does not have a medical or psychiatric condition that would limit their ability to comply with the behavioral recommendations of the program or pose a risk to the participant during weight loss, including meeting criteria for binge eating disorder,
• not pregnant or planning to become pregnant in the next 12 months,
• in the past 3 months changed the dosage of prescription medications that can cause a significant change in weight or appetite,
• have lost more than 5% of their weight in the past 6 months,
• willing and able to read in English,
• not participating in or planning to participate in other weight loss programs, and
• has not participated in our other ACT interventions. To increase follow-up data retention, eligibility criteria also include:
• willing to complete the follow-up survey, and (16) provide email, phone, and mailing address.

Exclusion Criteria:

• Opposite of the inclusion criteria