Carbohydrate Restriction and Prostate Cancer Growth

Inclusion Criteria: * Received prior radical prostatectomy or definitive local radiation for prostate cancer (either external beam radiation, brachytherapy, or combination) * PSA within the past 3 months is between 0.4 and 20 if prior radical prostatectomy, or between 3 and 20 ng/ml if prior radiation therapy. * PSA doubling time (PSADT) \>3 months and \<36 months 1. Calculated based at least 2 values (at least 0.2) in the prior 2 years with the first and last PSA separated by at least 3 months 2. Use all values in the last 2 years to calculate PSADT 3. PSADT calculated while NOT on androgen deprivation therapy (ADT). 4. If prior ADT use, then documented either A) normal testosterone or B) a testosterone within 50 points of normal and stable (defined as a second testosterone at least 6 weeks later that is equal or lower than the first testosterone) is required before starting to calculate PSADT. * BMI \>=24 kg/m2 * Willing to be randomized to a no-diet control or a low-carbohydrate diet * Reads, writes, and understands English Exclusion Criteria: * Anticipate needing secondary prostate cancer therapy within the next 6 months (i.e. radiation, or hormonal therapy) * Current use of weight loss medications including herbal weight loss supplements or enrolled in a diet/weight loss program * Currently on therapy aimed at lowering testosterone levels (includes gonadotropin-releasing hormone (GnRH) agonist/antagonist, prior bilateral orchiectomy, oral anti-androgens, or 5-alpha reductase inhibitors). Testosterone replacement is allowed but treatment should be stable during the entire study. * Known distant metastatic disease * Already consuming a carbohydrate-restricted or vegetarian diet * Unable or unwilling to adhere to a carbohydrate-restricted dietary intervention * Weight loss \>5% of body weight in the last 6 months * Medical comorbidities that in the opinion of the investigator limits the patient's ability to complete this study