Metabolic Impact and Compliance of Controlled, Varying, Mediterranean Diets in Pre-Surgical Prostate Cancer Populations (PROVISIONS)

Inclusion Criteria:

* Males 18 to 80 years old scheduled to undergo radical prostatectomy as per standard of care.
* BMI between 18.5 and 40
* Ability to read, write, speak, and understand English and/or Spanish.
* Ability to provide informed consent.
* Willingness to consume provided dietary interventions.
* Adequate organ and marrow function as assessed by treating clinician(s) which includes: White blood cell count (WBC) ≥2,500/microliter. Absolute neutrophil count (ANC) ≥1,500/microliter. Platelets ≥100,000/microliter. Hemoglobin ≥9 g/dL (transfusions permitted) Total bilirubin ≤1.5 x the institutional upper limit of normal (ULN). For subjects with Gilbert's disease ≤3.0 mg/dL. Aspartate aminotransferase (AST)/Alanine aminotransferase (ALT) ≤2.5 x institutional ULN. Creatinine clearance ≥51 ml/min as defined by Cockcroft-Gault equation.

Exclusion Criteria:

* Currently consuming a Mediterranean, lower carbohydrate, ketogenic, vegan, vegetarian, high fiber diet (14g fiber \> per 1,000 Calories) and/or any supplements (including herbal), vitamins, minerals, that would interfere with diets being tested in the study as determined by dietitian and/or investigators as these diets are highly restrictive and may impact objectives/outcomes in the trial.
* Previous intolerability to fiber-rich diets.
* Colitis, Irritable Bowel Syndrome, or other gastrointestinal condition per clinician discretion.
* Food allergies or other major dietary restrictions.
* Receiving active medical treatment for Type I or Type II diabetes mellitus.
* Recent weight loss or gain (both intentional and unintentional) as defined by 5%+ body weight in the last 30 days.
* Undergone any type of weight loss surgery.
* Any medical contraindications as determined by investigators.
* History of diabetic ketoacidosis.
* History of Gout.
* Patients that are immunosuppressed (transplant history, on immunosuppression, etc.) as per clinician discretion.
* Gallbladder removed or plan to remove per clinician evaluation.
* Other malignancies actively receiving systemic treatment as per clinician evaluation.
* Previous treatment for prostate cancer.
* Previous history of pelvic radiation.
* Patients with impaired decision-making capacity.