The main difference between Prolon and water fasts is that Prolon provides nutrition during the fast to decrease the risks of side effects and loss of lean body mass. The Prolon program has been designed to maximize safety and tolerance. Thus, we do not recommend undergoing a prolonged fast greater than a few days without direct supervision by an experienced healthcare practitioner.
In 2019, we conducted a safety survey of people who completed three or more rounds of Prolon, which found that:
- 84% of users did not report any negative experiences during their fast, and
- Of those who reported a negative experience, the most common symptoms were mild headache and fatigue
