The main difference between ProLon and longer fasts is that ProLon provides nutrition during the fast to decrease the risks of side effects and loss of lean body mass. While some people can tolerate fasts of longer than 5 days, the 5-day ProLon program has been designed to maximize safety and tolerability. Thus, we do not recommend undergoing a prolonged fast greater than a few days without direct supervision by an experienced healthcare provider.
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/lack of energy.
Our study of 3 consecutive rounds of ProLon also showed that the program helped people get rid of visceral/belly fat, while preserving lean body and muscle mass.