The purpose of this study is to test the hypothesis that an intervention of lifestyle modification will positively impact women with breast cancer who are overweight and/or obese. To that end, our primary endpoint is to examine the effects of a practical lifestyle intervention that can be implemented by overweight or obese women (BMI greater or equal to 25) with early stage breast cancer (I-III) on outcomes such as body weight and change in BMI over the course of the study.