Experimental Design and Methods This is a prospective, open labeled, randomized diet intervention study done on adult participants with PCOS. After signing informed consents, participants will be asked to eat a recommended ADA diet for two weeks (run in period). Participants will then have baseline testing, including: urine and blood tests to evaluate insulin resistance (fasting glucose and insulin, 2 hour oral glucose tolerance test), electrolytes to assess acid-base status, ovarian volume and testosterone levels measured to assess severity of PCOS, and questionnaires about menstrual frequency, eating habits and stress. Participants will then be randomized to either a high fruits and vegetable Paleo Diet for 8 months or a standard ADA-recommended diet for the first 4 months followed by Paleo Diet for 4 months. All testing will be repeated at 4 months (crossover point) and at completion of the diets at 8 months. The primary outcome variables are menstrual cycle frequency and ovarian volume, and secondary outcomes include metabolic profiles and eating/behavior questionnaires