This study investigates whether weight loss can prevent breast cancer from coming back in overweight and obese women. Breast cancer is a disease where cells in the breast grow out of control. The study involves women who have early-stage breast cancer and compares two different approaches to weight loss: a telephone-based intervention and a health educational control. The main goal is to see which approach is better at improving invasive disease-free survival, which means the cancer does not return or spread for a period of time.

Participants in the study will be randomly assigned to one of two study arms. In one arm, women will receive guidance and support through telephone calls to help them lose weight. In the other arm, women will receive health education materials. The study will monitor the participants' progress and health outcomes to determine the effectiveness of these interventions. The telephone-based intervention is an approach where participants receive counseling and support over the phone. This study does not involve any direct medical treatment but focuses on lifestyle changes.

• Who can participate: Women with a confirmed diagnosis of early-stage invasive breast cancer within the last 12 months, who are Her-2 negative and have a BMI of 27 or higher, can participate. They must be able to walk at least two blocks and not currently participate in another weight loss trial.
• Study details: Participants will be divided into two arms: one receiving a telephone-based intervention for weight loss, and the other receiving health education.