Impact of Ketogenic Diet on Tumor Microenvironment in Patients With Breast Cancer

Inclusion Criteria: * Be willing and able to provide consent for the study * Age ≥ 18 on the day consent is obtained * Eastern Cooperative Oncology Group (ECOG) score ≤ 2 * Patients must be postmenopausal the time of study entry * Stage I or II breast cancer using Tumor, Nodes and Metastasis (TNM) stage groups per American Joint Committee on Cancer (AJCC) 8th edition * Plan for upfront breast surgery with mastectomy or partial mastectomy and does not require pre-operative systemic therapy per standard of care * Must have tissue available from initial breast biopsy performed per standard of care * have the ability in the opinion of the investigator to adhere to a ketogenic diet and comply with study requirements such as ability to participate in telemedicine, utilize apps on a smart device, measure glucose/ketones at home, accurately log food intake and exercise, prepare food that is in line with ketogenic diet Exclusion Criteria: * Clinical indication for neoadjuvant therapy * Partial mastectomy or mastectomy planned for less than 3 weeks from study entry * Inability to comply with ketogenic diet * Consistent use of ketogenic diet within past 3 months * Participation in another diet program during study period * Nonepithelial breast malignancy such as sarcoma or lymphoma * Body Mass Index \< 18.5 * Comorbidities and/or active or ongoing illness that in the opinion of the investigator will limit patient's ability to safely participate in study * Type I diabetes * Use of ins…