The purpose of this study is to evaluate how a fasting-mimicking diet versus a usual diet influences cancer treatment of metastatic castrate-sensitive prostate adenocarcinoma. The fasting-mimicking diet is a 5-day program of plant-based products that the participant will consume to place the body into a fasting state. Examples of food products include soups, broths, energy bars, energy drinks, cracker snacks, herbal teas, and supplements. Preclinical work (research before studies with humans) has shown that a fasting diet can positively change the way the body responds to cancer treatment. In this study, researchers also aim to learn whether biomarkers change with a fasting diet. A biomarker is a biological molecule found in blood, other body fluids or tissues that may be a sign of a condition or disease and can be used to predict response to treatment. Participants will be randomly assigned to 1 of 2 groups. Group 1 will eat their usual diet, and Group 2 will eat a fasting-mimicking diet for 5 days in a row, every month for 6 months. Participants will also receive a Fitbit to be worn continuously during the study and will be asked to complete surveys and blood draws.