EMPOWER Men to Reduce Weight and Inhibit Prostate Cancer Progression

Inclusion Criteria: * Understand and voluntarily sign consent form * Able to adhere to study protocol * Demonstrated use of internet and email * Access to internet at least 4 days per week * Willingness to change diet, physical activity and weight * Willingness to be randomized to immediate start or standard of care * Histologically confirmed diagnosis of adenocarcinoma of the prostate with evidence of biochemical recurrence following local therapy (surgery and radiation will be allowed). Biochemical recurrence will be defined as a PSA \>= 0.2 ng/mL. * Surgically treated men must not be eligible for or decline salvage radiation. Men who recurred within 3 years of completion of salvage radiation will be included. * Definitive therapy (surgery or radiation) should be at least 4 weeks from time of consent. * Men who received prior hormone therapy with definitive local therapy (standard with radiation) are permitted if serum testosterone level is \>150 ng/dL and hormone treatment was discontinued \> 1 year from time of enrollment. * Body mass index \>= 25 kg/m2 * Eastern Cooperative Oncology Group (ECOG) performance status \< 2 * Willingness to return for clinical visit at 6 months, 12 months, and 24 months * Men receiving testosterone replacement therapy will be included if they are on a stable dose with testosterone levels in the normal range. Exclusion Criteria: * Any clinical or radiographic evidence of metastatic disease by computed tomography (CT) of the chest, abdomen and pelvis and technetium-99 bone scintigraphy (bone scan) * MI, stroke or ASCVD procedure within 6 months * Serious medical condition likely to hinder accurate measurement of weight, or for which weight loss is contraindicated, or which would cause weight loss * Unstable angina or medical conditional that would prevent routine exercise * Prior or planned bariatric surgery * Use of prescription weight loss medication (including off label use of medications) or over-the-counter orlistat within 6 months * Chronic use (at least past 6 months) of medications likely to cause weight gain or prevent weight loss (e.g. corticosteroids, lithium, olanzapine, risperidone, clozapine), including androgen deprivation therapy * Unintentional or intentional weight loss within 6 months of enrollment (≥ 5% of body weight)