Low Intensity Weight Loss for Young Adults

This is a 3-arm randomized controlled trial to test the efficacy of three novel motivational approaches to weight loss with 18-25 year olds. Participants will be 18-25 year olds with a BMI of 25-45 kg/m2, randomized to: 1) Behavioral Weight Loss (BWL), 2) BWL + Autonomous Motivation (BWL+Aut) or 3) BWL + Extrinsic Motivation (BWL+Ext). All arms will receive a 6-month behavioral weight loss intervention, followed by a 6-month no-treatment follow up period.

A 3-arm randomized controlled trial will be conducted, the goal of which is to determine which group represents the most viable approach to behavioral weight loss treatment with 18-25 year olds. A total of 381 participants,18-25 years of age, with a BMI between 25 and 45 kg/m2 will be randomized to one of three groups: 1) Behavioral Weight Loss (BWL), 2) BWL + Autonomous Motivation (BWL+Aut) or 3) BWL + Extrinsic Motivation (BWL+Ext). All arms will receive a 24-week behavioral weight loss intervention, including personalized dietary, physical activity, and weight loss prescriptions. In addition, all arms will be followed for a 6 month no treatment follow-up period. Assessments of weight and secondary outcomes will occur in 0, 3, 6 and 12 months. The investigators will compare treatment effects, across all 3 arms at 6 months, and compare arms on weight loss maintenance at12 months. The investigators will also examine mediators of treatment outcomes consistent with the investigators theoretical framework.

Eligibility Criteria:
Inclusion Criteria:

* Between 18-25 years of age. Body Mass Index (BMI) between 25 and 45 kg/m2. Men and women will be recruited. All race and ethnic groups will be recruited.

Exclusion Criteria:

* Report an uncontrolled medical condition that may pose a safety issue given the recommendations for diet and unsupervised physical activity in the current study (e.g., uncontrolled hypertension). The investigators will refer individuals who have blood pressure levels \>140 / 90 mmHg as part of baseline screening to their physician and exclude them from this study unless their treating physician determines s/he is a suitable candidate based on the specifics of the protocol and provides written medical consent for participation. Participants who report a history of or current treatment for medical conditions (e.g., hypertension, diabetes) will be asked to obtain MD consent to participate.
* Other health problems or medications which may influence the ability to walk for physical activity or be associated with unintentional weight change, including cancer treatment within the past 5 years or tuberculosis.
* Report a heart condition, chest pain during periods of activity or rest, or loss of consciousness on the Physical Activity Readiness Questionnaire (PAR-Q), which will be administered during prescreen. Individuals endorsing joint problems, prescription medication usage, or other medical conditions that could limit exercise will be required to obtain written physician consent to participate.
* Report a history of, or current diagnosis of anorexia nervosa or bulimia nervosa, or any current compensatory behaviors (e.g., vomiting, laxative use, excessive exercise).
* Current symptoms of alcohol or substance dependence.
* Planning to move from the area within the study period.
* Currently pregnant, pregnant within the past 6 months, currently breastfeeding or planning to become pregnant within the next 12 months.
* Hospitalization for depression or other psychiatric disorder within the past 12 months. History of psychotic disorder or bipolar disorder.
* Another member of the household is a participant or staff member on this study.
* Participation in another research study that may interfere with this study.
* Currently participating in a weight loss program and/or taking weight loss medication or lost \> 5% of body weight during the past 3 months.
* Failure to complete the screening appointments.