This pilot clinical trial studies a pancreatic nutritional program for helping patients with stage I-III breast cancer who are overweight or obese lose weight. When patients have a high level of sugar in their blood, due to eating sugary foods and/or a sedentary lifestyle, the pancreas needs to work harder to digest the sugar. This can cause weight gain, obesity, and other illnesses. Breast cancer patients who are overweight and obese are more likely to have their breast cancer return. The pancreatic nutritional program is a diet and lifestyle intervention that helps protect the pancreas by keeping blood sugar levels low, and may help patients achieve sustained weight loss, improved health, better quality of life, and possibly a better outcome to their treatment.

PRIMARY OBJECTIVES:

I. To estimate the change in body weight at 6 months post-intervention relative to baseline.

SECONDARY OBJECTIVES:

I. To examine changes in: body composition; body chemistry; physical fitness; inflammatory markers; deoxyribonucleic acid (DNA) repair capacity; and quality of life per the Functional Assessment of Cancer Therapy - Breast (FACT-B)+4, version 4 questionnaire at 6 months post-intervention relative to baseline.

II. To describe adverse events possibly related to wearing the glucometer sensor or following the pancreatic nutritional program (PNP) diet.

III. To document compliance with the various components of the PNP (wearing the glucometer sensor; recording body weight; completing journal entries; completing meal cards; attending weekly counseling sessions with diet instructor).

OUTLINE:

Patients participate in the PNP intervention, which begins with a baseline meeting with a diet and lifestyle instructor to discuss baseline testing results, begin an educational plan, determine an individualized eating plan, and print out food choices. Patients also undergo automated glucometry every 15 minutes, review their individual food choices and blood glucose levels 90 minutes after eating, keep a daily nutrition and lifestyle journal log, fill out a daily meal discovery card log, and attend weekly meetings with a diet and lifestyle instructor for 12 weeks.

After completion of study, patients are followed up within 1 week and then at 6 months.

Inclusion Criteria:

• Patients with early-stage breast cancer (stage I-III)
• Patients who have or have not undergone chemotherapy are both eligible; if the patient has undergone chemotherapy she must have completed adjuvant chemotherapy for >= 3 months and =< 5 years prior to study enrollment
• Postmenopausal women defined by either: natural menopause with at least one year since last menses, or chemotherapy-induced menopause with at least one year since last menses and follicle-stimulating hormone (FSH) and estradiol levels within the postmenopausal range
• Body mass index (BMI) of 25-33 kg/m^2
• Patients must be willing to adhere to the PNP intervention and the entire 6-month study
• All patients must have the ability and the willingness to sign a written informed consent

Exclusion Criteria:

• Patients who are diabetic
• Patients whose BMI falls outside the eligible range (< 25 kg/m^2 or > 33 kg/m^2)
• Patients with stage IV breast cancer
• Patients with Rheumatoid Arthritis and other inflammatory diseases that would impact correlative studies