OUTLINE: This is a randomized study. Patients are randomized to one of 2 arms (dietary fat reduction with and without increased fiber). All patient must successfully complete a dietary run-in phase for 4 weeks before randomization. During the run-in phase, patients are asked to maintain a food record for days 7-14. Patients undergo radioisotopic infusion study of sex steroid metabolism on days 14, 21, and 28. Patients are given 3 prepackaged meals a day for 12 weeks. Patients must maintain a record of all food eaten and return all food containers to the center for documentation. Patients undergo radioisotopic infusion study of sex steroid metabolism on days 70, 77, and 84. At the end of the 12 weeks, patients meet with the dietitian for 30 minutes to receive instructions on maintaining a low fat, high fiber diet for the second phase of the study.