The exact same information, content, schedule, and 30 minute sessions will be provided to telephone-based participants as offered to participants who receive in-person counseling. Participants will be taught diet, exercise and behavior change strategies via the telephone (weekly calls for month 1, every other week for months 2-3, and monthly for months 4-6). All lessons and diet and physical activity logs will be mailed to them at the beginning of the program. Participants will record their daily diet and exercise in the logs.

At 6-months the participants in the Wait List group may choose to participate in the 11 sessions either in-person or via telephone or a combination of the two modes of delivery. They will also be offered the opportunity to return to Yale at 12-months (immediately after the end of the 6-month counseling sessions) to have weight and DEXA measured.

The intervention will be based on the Diabetes Prevention Program weight loss program, which uses a combination of reduced caloric intake, increased physical activity, and behavior therapy. The content of the weight loss program will be similar for the in-person and telephone interventions, but the approach will vary (i.e., in-person vs. telephone counseling). The weight loss intervention will be conducted by a Registered Dietitian, who has training in exercise physiology and behavior modification.

BMI will be calculated using weight and height measurements (weight (kg)/height (m)^2 ). Weight and height will be measured by research staff blinded to the participant's randomization group at baseline and 6-months. Participants will be weighed in light indoor clothing, without shoes, rounding up to the nearest 0.1 kg; height will be measured in a standard manner, without shoes, using a stadiometer, rounding up to the nearest 0.1 cm. All measures will be performed and recorded twice in succession.

Participants will be weighed in light indoor clothing, without shoes, rounding up to the nearest 0.1 kg. All measures will be performed and recorded twice in succession.

Dual Energy X-Ray Absorptiometry (DEXA) scans will be performed at baseline and 6-months. The DEXA measurements will be made with a Hologic scanner (Hologic 4500 with a "Discovery" upgrade, Hologic Inc, Waltham, Mass). A whole-body scan takes approximately 10 minutes to complete. We will measure percent body fat utilizing DEXA.

We will collect a breast tissue biopsy from the unaffected breast at baseline and 6 months. Six slides will be made from each specimen for immunohistochemistry, as follows: Ki67 (MIB-1, DAKO), IGF1 receptor (1D5; DAKO), insulin receptor (mouse anti-human monoclonal B1445; LifeSpan BioSciences), Estrogen receptor (SP1, NeoMarker), Progesterone receptor (pgR636, DAKO) and HER-2 neu (SP3, NeoMarker). Ki67 will be scored quantitatively (% positive nuclei) using the Aperio system (Specialized Histopathology Laboratory). Estrogen and progesterone receptors will be scored following current ASCO/CAP guidelines (percent positive, intensity). Her2 will be scored according to current ASCO/CAP guidelines (intensity of membrane staining). All other markers will be scored on a semi-quantitative scale (0 to 3+).

All the hormones to be measured (insulin, IGF-1, leptin, adiponectin and C-reactive protein) have been previously measured in our lab and published. We will use immunoassay techniques and kits from Diagnostic Products Corporation (DPC, Los Angeles, CA) to measure each hormone value. Each woman's baseline and follow-up samples will be used in the same batch, and an equal number of intervention and control samples will also be included in the same batch. Blind duplicates are also included in and between batches to estimate coefficient of variations.

The 7-Day Daily Activity Log (7-Day DAL) will be the primary measure used to compare physical activity levels at baseline and 6-months among the three groups. All participants will complete the log for seven consecutive days, recording the amount of time spent in moderate- to vigorous-intensity recreational exercise. We will calculate their total minutes per week of exercise. Participants randomized to in-person and telephone counseling will also complete the 7-day DAL weekly.