The purpose of the study is to demonstrate that breast cancer survivors who need to lose weight are able to follow a weight loss program which combines modest calorie restriction with a graduated activity program..

Feasibility will be assessed by 1) the number of women that complete the 3--month program; 2) the number of women that can achieve the targeted amount of physical activity per week by the end of the program; and 3) the median amount of physical activity achieved group by all subjects that complete the program.

Inclusion Criteria:

• Women < age 71 in good general health.
• Prior diagnosis of breast cancer.
• At least 3 months from completion of any cytotoxic chemotherapy or radiation or surgery. May continue to take endocrine therapy and/or maintenance trastuzumab.
• Body Mass Index (BMI) 30-45 kg/m2.
• By self-assessment, currently performing 60 minutes or less of purposeful exercise per week but able to walk at least 30 minutes on a level surface.
• Access to a smart phone capable of running MyFitnessPal and Garmin Connect apps and willing to have diet and exercise data from these apps viewed by study personnel.
• Live in the greater Kansas City Metropolitan Area
• Willing and able to perform moderate intensity exercise at least 5 days per week for 3 months.
• Willing to perform unsupervised home exercise for the entire 3 months.
• Willing to participate in a weekly behavioral modification group phone call for 3 months.
• Willing to participate in a controlled dietary intervention with portion controlled meals and partial meal and track food intake and exercise.

Exclusion Criteria:

• Use of metformin, insulin, steroids or weight loss or anti-psychotic drugs within the prior 3 weeks
• Individuals with prior bariatric surgery procedures
• Need for chronic immunosuppressive drugs
• Participation within the past 6 months on a structured weight loss program such as Weight Watchers®
• Physical impairments (bad hip, knees, feet, peripheral neuropathy) that would prohibit performing moderate intensity exercise at least 5 days per week.
• Any other condition or intercurrent illness that in the opinion of the investigator makes the subject a poor candidate for participation in the trial such as recent cardiac event.
• Currently receiving investigational agents in a clinical trial.