There are many ways to practice water fasting, but experts agree that the ideal duration is five days, once a year. For those new to water fasting, an initial period of 24 to 48 hours is recommended.

Extended water fasting is trending, but experts warn it may be a risky path with dangerous health consequences.

There's less research, however, on long-term water-only fasting for periods of five days or more. But that doesn't stop advocates from making astounding claims anyway. One such fasting guru is ...