This is a single-arm longitudinal group to examine patient-reported outcomes, body mass and mammographic density changes pre- and post- weight loss intervention of breast cancer survivors using video conferencing telehealth visits.

Participants will receive weekly group sessions of lifestyle counseling for the first 20 weeks, followed by every other week sessions in weeks 22 and 24, for a total of 6 months of intervention. These group sessions, with 6 participants per group, will be delivered virtually via a HIPAA Compliant Teleconference Platform. The expected number of participants is at least 2 and no more than 6 in this 90-min group sessions which will be provided by a counselor from Penn Center for Weight and Eating Disorders.

The content of the sessions addresses the domains associated with behavioral weight management, including nutrition, exercise, stress and emotion management, and lifestyle modification strategies (to improve adherence to the diet and activity plan). Participants will monitor energy intake and physical activity daily to help them achieve recommended calorie and activity goals. Self-monitoring will be encouraged online with MyFitnessPal.com, which will be shared with the study staff to increase accountability and provide opportunity for feedback to participants.

Each participant will also be mailed a digital scale so they can weigh themselves each week and report their weight to the group leader. Participants will be encouraged to start with at least 10 minutes of moderately vigorous physical activity (e.g., brisk walking, swimming), at least five days per week, building up to at least 30 minutes per day (150 minutes per week) by week 6.

The primary objective is to assess feasibility and acceptance of telehealth weight loss intervention by the participants. The participants will be asked to complete the following surveys at two time points: baseline (pre-) and treatment end (at week 24). The participants will complete the following psychosocial measures.

1. City of Hope Quality of Life (COH-QOL) Instrument - Breast Cancer Patient (QOL-BC)
2. The International Physical Activity Questionnaire (IPAQ) Short Form - that assess the types and intensity of physical activity and sitting time in which people routinely engage. It provides an estimate of total physical activity in MET-min/week and time spent sitting.
3. Patient Health Questionnaire (PHQ-9) (Depression)
4. Acceptability of Intervention Measure

Finally, investigators will conduct an exit interview with each participant to assess the acceptability of the intervention, the delivery of the intervention via telehealth, and the patients' satisfaction with their treatment outcomes. Investigators will also solicit suggestions for improvements to the program for future interventions.

The secondary objectives are to measure changes from pre- to post weight-loss intervention for 1) body mass and 2) mammographic breast density.

To assess body mass changes, weight will be reported at baseline and after week 24 of the intervention. The scale will be mailed to participants at the beginning of the study. Participants' height from the electronic medical record will be used. Percent weight loss will be calculated to assess weight change across participants.

To assess mammographic breast density changes, investigators will measure mammographic density of annual mammogram pre- and post weight-loss program. Annual mammograms are routinely performed for breast cancer survivors except for those who have had bilateral mastectomy. Two annual mammograms will be used to measure mammographic density. The annual mammogram performed between 1 month - 12 months prior to weight loss program initiation will be used as baseline (pre-intervention). The post-intervention mammogram will be the first annual mammogram performed after weight loss program. If routine annual mammogram occurs during the 20-week weight loss program, then the next annual mammogram will be used for breast density assessment.

Therefore, study duration for each participant from enrollment to completion (mammographic density) is estimated to be up to 24 months.

Inclusion Criteria:

• History of in situ or invasive breast cancer
• Have completed breast cancer surgery, adjuvant cytotoxic chemotherapy (as indicated) and adjuvant radiation therapy (as indicated) at least 6-months prior to enrollment
• Not on active treatment for other cancer for at least 6-months prior to enrollment
• Currently cancer free
• Overweight or obese (BMI of 25 kg/m^2 or greater)
• Have internet access and videoconferencing capability

Exclusion Criteria:

• Current use of weight loss medication (OTC or prescription) or participation in behavioral weight loss program
• Currently participating in a behavioral weight loss program
• Self-report of alcohol or substance abuse within the past 12-months, including at-risk drinking (current consumption of more than 14 drinks per week)
• Undergone bilateral mastectomy
• History of Bulimia nervosa
• Inability to provide informed consent

12 patients (and possibly up to 20) (2 telehealth groups with at least 6 participants; 1 group leader per group)