The study aims to investigate whether following a controlled Mediterranean-style diet prior to robotic-assisted radical prostatectomy surgery in patients diagnosed with prostate cancer affects fasting insulin levels and other values that can be measured in blood and tissue samples from surgery.

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.