Gut Microbiome, Adverse Effects, and Markers Through MEtabolic Reprogramming

Inclusion Criteria:

* Diagnosed with histologically-confirmed stage I-III invasive carcinoma of the breast
* Planning for standard neoadjuvant or adjuvant chemotherapy ddAC or TC for 4 cycles (concurrent anti-HER2 therapy is permitted)
* Provider physical exam within 4 weeks of consent
* Eastern Cooperative Oncology Group (ECOG) 0-1 (as per recent provider note or direct confirmation with provider)
* BMI ≥ 19.5 kg/m2 (as per most recent visit documented in medical record)
* Willingness to change diet, and provide fecal sample 3 times during study

Exclusion Criteria:

* BMI \<19.5 kg/m2
* Diabetes
* History of eating disorder
* Serious/uncontrolled medical condition (e.g. end stage renal disease on dialysis, cirrhosis, uncontrolled hypertension, seizure disorder, history of bariatric surgery)
* Pregnant or nursing
* Use of medications that must be taken with food: allopurinol, aspirin, amiodarone, baclofen, bromocriptine, carvedilol, carbamezpine, cimetidine, diclofenac, doxycycline, fenofibrate, fludrocortisone, glyburide, hydrocortisone, iron supplements, ketorolac, lithium, methylprednisolone, naproxen, niacin, potassium salts, prednisone, procainamide, sevelamer, sulfasalazine, trazodone, valproic acid