The purpose of this study is to compare standard Behavior Therapy (BT), BT plus Meal Replacements (MR) and a condition focusing on the nutritional changes to the home food environment (HFE) on weight loss, weight loss maintenance, nutritional composition of the diet and psychosocial outcomes. A second aim is to determine the degree to which the specific targets of the experimental interventions do in fact change in the anticipated direction during the intervention and to evaluate whether such changes might account for improvements in weight loss maintenance. This study is important because it could provide the first evidence that the current standard of care for obesity lifestyle treatment could be improved by the addition of MRs or a program of comprehensive nutritional change.

Inclusion Criteria:

• Male and female participants between the ages of 18 and 65
• body mass index (BMI; kg/m2) between 27-45
• able to travel regularly to the study location
• interested in participating in a weight loss program.

Exclusion Criteria:

• currently enrolled in another organized weight loss program
• lactose intolerance
• taking medications that affect appetite (unless dosage had been stable for at least the previous six months)
• history of gastric bypass or other surgical weight loss procedures
• medical conditions (e.g., cancer, substance abuse, psychotic disorders) that could limit their ability to comply with the behavioral recommendations or pose a risk to the participant during weight loss
• pregnancy or planning to become pregnant during the next two years -
• breastfeeding
• consuming an amount of alcohol that could interfere with study completion