This randomized controlled trial of weight loss interventions in overweight and obese women with early stage breast cancer consists of two arms, please see the arms section for more information. Patients will be randomized 1:1 within stratification factors: menopausal status (premenopausal vs. postmenopausal), hormone receptor status of the tumor (ER and/or PR positive vs. ER and PR negative), and race/ethnicity (African American vs. Hispanic vs. Other). The primary objective of this trial is to compare the effect of the telephone-based intervention versus a health educational control on invasive disease-free survival (IDFS). The total sample size is 3136 patients. Patient follow up for primary and secondary endpoints will continue to a maximum of 10 years, as per the standard protocol for cooperative group adjuvant trials.