Pilot randomized controlled parallel group behavior change comparative effectiveness trial involves 30 breast cancer survivors interested in losing excess body fat. Both interventions include dietary + exercise prescriptions that hold promise for reducing the survivors' risk of cancer recurrence. Both interventions are consistent with the Dietary Guidelines for Americans but the Diabetes Prevention Program (DPP)-based approach focuses on weight loss through calorie restriction and increased physical activity while the Highly Microbiota-Accessible Foods (HMAFs) approach is intended to be a low-numeracy version of a Mediterranean-style diet and increased physical activity. The DPP approach is considered to be a high-numeracy intervention because it requires that consumers keep track of all calories consumed and expended per day and to endeavor to maintain a calorie deficit each day during the active weight loss phase. For both conditions, the 12 to 13-week intervention includes 2 virtual home visits, 2 virtual group education sessions and 7 telephone or Zoom-based coaching sessions by well-trained intervenors. Assessments occur at baseline and six months, with systemic inflammation (high sensitivity C-reactive protein) being the primary outcome measure and visceral fat being a secondary outcome. Other prespecified secondary outcomes include gut microbiota alpha-1 diversity, insulin resistance, HDL-cholesterol, daily count of highly microbiota-accessible foods, waist circumference, BMI, systolic blood pressure, ratio of fecal Proteobacteria to short chain fatty acid-generating bacteria and health-related quality of life.

Background. The human gut microbiota influences obesity status and inflammation, two major risk factors for postmenopausal breast cancer recurrence. Whether an exercise and dietary intervention designed to optimize gut microbiota composition might reduce risk for breast cancer recurrence is unknown. To improve the gut microbiota composition, the investigators propose teaching postmenopausal breast cancer survivors to allocate about 20% of their daily calorie intake to consuming a daily count of six fiber-rich, minimally processed, plant-based food choices that comply with federal MyPlate.gov diet recommendations. Preliminary data suggest that the investigators' Highly-Microbiota-Accessible Foods (HMAFs) approach will yield cardiometabolic outcomes equal to or better than those achieved by the traditional Diabetes Prevention Program (DPP) calorie restriction approach at 6 months follow-up. Because breast cancer recurrence risk covaries with cardiometabolic risks, the lower cardiometabolic risk of the HMAFs approach should be associated with reduced risk of breast cancer recurrence.

Hypotheses. The greater diversity of fiber-rich, minimally processed plant foods consumed in the HMAFs condition relative to the DPP condition will result in greater changes in HMAFs participants compared to DPP participants from baseline to 6 months follow-up in the following measures: (primary hypothesis) reduce high sensitivity C-reactive protein, (secondary hypotheses) reduce visceral body fat and increase alpha-1 diversity of gut microbes and increase health-related quality of life.

To test these hypotheses, the research objectives include the following specific aims: 1) Recruit a diverse sample of 30 overweight or obese postmenopausal survivors with stage I, II and IIIa breast cancer; randomly allocate them to two lifestyle change intervention conditions, 2) Obtain baseline and 6-month follow-up assessments of: low grade systemic inflammation, body composition including visceral fat estimation, cardiorespiratory fitness, inflammatory and cardiometabolic biomarkers, fecal samples, and quality of life, 3) Conduct two parallel, three-month behavior change interventions, contrasting the 6-count HMAFs approach with the traditional DPP calorie restriction approach , and 4) Use results to design a ramped-up randomized factorial trial.

If hypotheses are confirmed, the low-numeracy HMAFs approach may, for low-income survivors, be a practical alternative to traditional high-numeracy calorie restriction approaches to reducing risk of breast cancer recurrence.

Inclusion Criteria:

1. At least 6 months since breast cancer diagnosis and up to 4 years since diagnosis.
2. Between 50 and 75 years of age.
3. Diagnosed with localized steroid hormone receptor-positive breast cancer, up to stage IIIa.
4. At least 6 months post chemotherapy or radiation treatment.
5. Subjects must be in good health as determined by medical history, physical examination, and clinical laboratory measurements.
6. No broad-spectrum antibiotic use in the last two months.
7. Body mass index between 27 and 38 based on self-reported height and weight and between 25 and 40 based on objective assessment of height and weight.
8. Willing to complete assessments at baseline, 3 months and 6 months follow-up

Exclusion Criteria:

1. Diagnosed with metastatic breast cancer
2. Currently undergoing chemotherapy or radiation treatment
3. Immunoglobulin-E (IgE)-mediated food allergies, or any medical condition requiring mandatory dietary restrictions
4. Significant cardiac, pulmonary, renal, liver or psychiatric disease.
5. Muscular, orthopedic, or cardiovascular limitations that would prevent full participation in exercise

De-identified data will be posted on the website of the UCLA Fielding School of Public Health for access by students and other investigators. Primary and secondary outcomes and demographic characteristics will be shared.

The data will become available 1 year after the completion of the final report.

Bona fide researchers as determined by the University of California-Los Angeles (UCLA) Institutional Review Board (IRB) will be eligible to use the data.

All assessments will be conducted by project personnel blind to the study participants' randomization status. The investigators responsible for helping participants complete the Automated Self-administered 24-hour (ASA 24) dietary recalls and for assessing their body composition via dual x-ray absorptiometry (DXA) will be kept blind to the study participants' randomization status. Investigators will be kept blind to participant assignment to condition by having the two health coaches refer to their patients by an arbitrary, unique study identifier during weekly debriefings when the study progress by individual participants might be discussed.