OUTLINE: This is a randomized, multicenter study. Patients are stratified by center, nodal status, ER status, and type of adjuvant chemotherapy. The first group receives intensive dietary intervention for reduction of total fat intake to 15% of calories, with repeated individual and group counseling sessions. The second group receives USDA/DHHS dietary guidelines and minimal intervention. All patients who are estrogen receptor positive receive concurrent therapy with tamoxifen; cyclophosphamide, methotrexate, fluorouracil (CMF) followed by tamoxifen; doxorubicin, cyclophosphamide (AC) followed by tamoxifen; fluorouracil, doxorubicin, cyclophosphamide (FAC, CAF) followed by tamoxifen; or AC, paclitaxel followed by tamoxifen. Patients are followed annually throughout the study.