Behavioral Weight Loss and Exercise After Treatment (BEAT)

Inclusion Criteria: * Breast cancer diagnosis * Received surgery +/- chemotherapy +/- radiation for treatment of a Stage I, II or III breast cancer. Ongoing treatment with monoclonal antibodies and/or anti-estrogen therapy is acceptable * Completion of initial therapy 6 weeks prior to study initiation * BMI of 27-45 kg/m\^2 Exclusion Criteria: * Prior diagnosis of malignancy other than non-melanoma skin cancer (i.e. prior non-melanoma skin cancer is not an exclusion criteria) * Medical conditions that limit food choices such as celiac sprue or inflammatory bowel disease * Inability to walk on flat ground (or a treadmill) at 2.5 mph for 5 minutes * Age \<21 and \>70 * Presence of body metal * Psychotic or central nervous system impairment that would limit compliance with study requirements, including dementia * Evidence of metastatic disease * Symptomatic heart disease (chest pain or equivalent with activity) * Exercise limiting pulmonary disease or need for oxygen to exercise * Individuals taking mood stabilizing medications including: Lithium, valproic acid, also called divalproex sodium (Depakote), carbamazepine (Tegretol), lamotrigine (Lamictal), oxcarbazepine (Trileptal), olanzapine (Zyprexa), aripiprazole (Abilify), risperidone (Risperdal), ziprasidone (Geodon), clozapine (clorazil) * Participants with an active neurologic disorder that affects the central nervous system, including seizures, and Parkinson's disease * Weight loss of \>10 lbs in the previous 6 months * Participation in \> 150 minutes of moderate intensity activity by self report, unless activity level by accelerometer is less than 150 minutes of moderate intensity activity