“If you don’t have cancer and you do a therapeutic fast 1 to 3 times per year, you could purge any precancerous cells that may be living in your body.” If you’re over the age of 40, cancer is one of the four types of diseases (see Dr. Peter Attia here) that will kill you with 80% certainty, so this seems like smart insurance. There is also evidence to suggest—skipping the scientific detail—that fasts of 3 days or longer can effectively “reboot” your immune system via stem cell–based regeneration. Dom suggests a 5-day fast 2 to 3 times per year.