ADF · Every-Other-Day Protocol
Fast every other day. Strong cardiovascular data, hard to sustain long-term.
Fasting
Caution Advised
12 protocols. 1 rest on strong human evidence. Ordered with the best evidenced first.
12 protocols in Caution Advised
The Muscle-Preserving Medical Fast
A medically designed fast that keeps protein high to protect muscle while driving rapid fat loss, effective but requiring supervision.
Two-Day Water Fast
The midpoint of extended fasting. Deep ketosis, strong autophagy, manageable for many.
Three-Day Water Fast · Deep Autophagy Tier
At 72 hours, growth hormone surges 300%, autophagy peaks, and the immune system begins to reset.
What Fasting Does (and Doesn't) Do for the Gut
The real digestive physiology behind fasting, gut motility and microbiome shifts, separated from "gut reset detox" marketing.
One Meal A Day · 23:1 Protocol
The most extreme daily fast. 23 hours off, one meal on. Simple, effective, and easy to do badly.
20:4 · Undereat by Day, Feast by Night
The original modern long-fast template. Eat a little by day, feast in a four-hour window at night.
Prolonged Water-Only Fasting
Five to seven days, water only. Deep fasting territory that belongs under medical supervision.
Modified Fast · Broth-Only Protocol
Not a true fast. A low-calorie broth protocol that eases the experience while blunting some benefits.
Absolute Fast · No Food or Water
No food and no water. Heavily promoted, poorly evidenced, and genuinely risky beyond a day.
Bulletproof-Style · Fat-Only Window
Add fat to extend a fast. Eases ketosis and hunger, but the "fat does not break a fast" claim is contested.
Juice Cleanse · Liquid-Only Protocol
Marketed as detox, delivered as a sugar load. The most commercially hyped, least fasting-like protocol.