Brief Summary: RATIONALE: A diet and physical activity program followed by a weight-loss maintenance program may help obese black women lose weight. It is not yet known whether a weight-loss program is more effective than a general health education program in helping obese black women lose weight. Weight loss may reduce a person's risk of developing cancer. PURPOSE: This randomized phase III trial is studying a weight-loss program to see how well it works in helping obese black women lose weight.

Detailed Description: OBJECTIVES: Primary * To estimate the effectiveness of a 24-week diet and physical activity intervention and a 1-year maintenance intervention designed to produce and maintain weight loss in obese black women. * To estimate the effect of these interventions on changes in fasting serum insulin, glucose, and free IGF-1, IGFBP-1, and IGFBP-2 levels as well as total IGF-1 and IGFBP-3 levels. Secondary * To compare changes in dietary consumption of total calories, total fat, fruits, vegetables, and fiber as well as physical activity in participants undergoing a weight-loss intervention vs a control intervention. * To compare changes in knowledge, attitudes, self-efficacy, and social support related to diet, physical activity, and weight loss in participants undergoing a weight-loss intervention vs a control intervention. * Assess the efficacy of a weight-loss intervention mechanism and the association between weight loss and weight loss maintenance with potential biologic mediators of breast cancer risk. OUTLINE: Participants are randomized to 1 of 2 intervention arms. * Arm I (weight-loss intervention): Participants undergo a combined weight-loss intervention (diet and physical activity) over 24 weeks comprising individualized sessions with an interventionist once monthly and group sessions twice weekly. During the group sessions, participants receive information about diet, physical activity, and weight loss and take part in exercise classes. Participants receive handouts, food-measuring tools, and pedometers. Participants also discuss goal setting and problem solving. During the individualized sessions, participants undergo motivational interviewing (MI) to assess their individual needs and to motivate them to make or sustain behavioral changes. Beginning 1 month after completion of the combined weight-loss intervention, participants undergo a weight-loss maintenance intervention over 12 months. Participants continue their exercise classes twice weekly and receive a copy of the aerobic exercise class videotape for use at home. Prior to each exercise session, participants may share their weight-loss experiences (e.g., successes, struggles) or a motivational or informational story, article, or prayer with other group members. Participants also receive weekly newsletters that include information presented in the original weight-loss intervention, opportunities in the community for physical activity (e.g., ice skating, swimming, or local walks), and further advice on maintaining weight loss. Participants undergo 4 MI sessions over the telephone that address diet, physical activity, and weight-loss maintenance strategies. The MI sessions also provide an opportunity for individualized problem solving. * Arm II (control intervention): Participants undergo a control intervention over 24 weeks comprising weekly newsletters on general health topics, such as first aid, smoking cessation, cancer screening, and disease prevention, and monthly general health classes that demonstrate information conveyed in the newsletter (e.g., first-aid techniques). After completion of the control intervention, participants undergo a control maintenance intervention over 12 months comprising a monthly newsletter on general health topics. After completion of the maintenance intervention, participants undergo 10 intervention sessions and receive the same study-related materials (handouts, food-measuring tools, and pedometers) as in arm I. Blood samples are collected at baseline, 24 weeks, and 18 months for laboratory biomarker studies. Samples are analyzed for insulin levels by radioimmunoassay, glucose concentrations, and total and free IGF-1, IGFBP-1, IGFBP-2, and IGFBP-3 by enzyme-linked immunoassay. Participants complete questionnaires at baseline, 24 weeks, and 18 months to assess diet, physical activity, cognitive measures (attitudes, beliefs, and self-efficacy), social support, and environmental measures.