This project compares gold standard cognitive-behavioral therapy (based on LEARN, Diabetes Prevention Program, LOOK Ahead) used in both research and clinical settings, with acceptance-based behavioral therapy for weight loss. Standard behavior treatment (SBT) focuses on modifying eating, thinking, and activity levels. Participants limit their daily caloric intake, keep food records, increase physical activity, and practice weight control behaviors, such as stimulus control, cognitive restructuring, alternative coping skills, and distinguishing hunger from cravings. The acceptance-based approach (ABT) incorporates the behavioral and nutritional components, but replaced the cognitive and motivational components with components that are consistent with an acceptance-based approach, such as acceptance and willingness to experience cravings, cognitive defusion, mindfulness training to interrupt automatic eating, and values work. These components are drawn from Acceptance and Commitment Therapy (ACT; Hayes, Strosahl, & Wilson, 1999), a cognitive-behavioral therapy that has been gaining increasing attention and empirical support (Bach & Hayes, 2002; Bond & Bunce, 2000; Hayes et al. 2004). Though relatively new, acceptance-based strategies have demonstrated effectiveness in helping individuals to respond to unwanted thoughts and feelings (Hayes, Rissett, Korn, Zettle, Rosenfarb, Cooper, & Grundt, 1999, Keogh, Bond, Hanmer, & Tilston, 2005) and offer a novel alternative to control-based strategies (such as distraction and confrontation).

Participants in this study will be randomly assigned to either the traditional behavioral therapy condition (SBT) or the acceptance-based behavioral therapy condition (ABT). Both conditions are delivered in group format. A total of 30, 75 minute sessions will take place over the course of 40 weeks.

Specific Aims

1. To evaluate the feasibility and acceptability of the treatment, and its short and moderate-term effectiveness relative to the current gold standard behavioral treatment (SBT).
2. To evaluate the effectiveness of ABT with novice clinicians and with weight control experts.
3. To evaluate the effectiveness of ABT would be moderated by mood disturbance, emotional eating, disinhibition or susceptibility to food stimuli.

Inclusion Criteria:

• Ages 18 to 65
• Fluent in English
• Body mass index (BMI) of 25 kg/m2 higher
• Agrees to not join another weight loss program for 9 months

Exclusion Criteria:

• Lactating, pregnant, or planning to become pregnant in the next two years
• Currently taking a medication or having medical/psychiatric problem known to cause weight loss or weight gain (unless medication is long-term and dosage is unchanging - e.g., Synthroid)
• A medical or psychiatric condition that limits ability to comply with the program's behavioral recommendations (including physical activity)
• Current or history in the past ten years of an eating disorder
• Plans to leave the Philadelphia areas within the next nine months.