Plant-Based Nutrition for Breast or Endometrial Cancer

Inclusion Criteria: • Female sex (as assigned at birth), aged 18 years or older * A confirmed diagnosis of endometrial or metastatic breast cancer. All subtypes are eligible * Treating oncologist approval and expected survival of at least six months * Undergoing any systemic treatment including hormonal, cytotoxic, targeted monoclonal antibody or small molecule kinase inhibitors or any combination of the above. Women who have active cancer and have been recommended but declined systemic treatment are also eligible. * Willing to adopt a strict, whole-foods, plant-based diet * Willing and able to comply with the WFPB protocol for the duration of the study including scheduled testing, Zoom meetings, and office visits * Able to speak and read English fluently. * Women with plans for radiation therapy or surgery are also eligible provided that they meet all other eligibility criteria. Exclusion Criteria: • BMI ≤ 20.0 kg/m2 * Inability to tolerate a normal diet * Active malabsorption syndrome at time of consent, as determined by study physicians (i.e. Crohn's disease, bowel surgery) * Any food allergies or intolerances that would interfere with study compliance * Recent consumption (in the past six months) of a vegan diet * eGFR \< 30 on ≥ two lab tests in the past six months * Serum potassium \> 5.4 in the past six months * Current insulin or sulfonylurea use * Current warfarin use (non-vitamin K antagonist allowed) * High-risk alcohol use (\>7 drinks/wk) * Illicit substance us…