Stop eating all day: what fasting researchers say about snacking and late meals
September 27, 2026 · 25 min read
Jason Fung, Satchin Panda, William Li and Huberman converge on a practical rule: compress eating into a daytime window and give the body roughly 12 or more hours overnight without food. The timing of meals, not just their content, appears to shape insulin, fat burning and circadian health.
The rules, numbers and steps worth keeping in front of you.
- Core rule (all four): no grazing, eat nothing late, and keep a long overnight stretch with no calories, about 12 hours or more.
- Fung: three meals a day, no snacks and long breaks between meals. He says constant eating keeps insulin high and blocks fat burning.
- Panda: take all food and drink calories within a consistent 8 to 12 hour window. He says 12 hours suits almost anyone.
- Li: stop eating about three hours before bed and wait at least one hour after waking. Add eight hours of sleep and you reach 12.
- Huberman: no calories for two to three hours before bed and no food for the first hour after waking.
- Huberman: you reach the fasted state about five to six hours after your last bite, not when you stop eating.
- Panda: even a tiny bite, under 5% of a meal, moves mice from fat burning back to carbohydrate burning.
- Keep the same window every day. Huberman says weekend drift works like jet lag and takes two to three days to recover from.
- Huberman: most people underestimate their window by an hour or two, so aim one to two hours shorter than your target.
- Don't go under eight hours if you train hard, are under heavy stress, or want to keep a regular cycle or conceive (Panda, Huberman).
- Water, black coffee and tea don't break a fast. Panda notes coffee on an empty stomach can cause reflux or anxiety in some people.
- Timing works alongside food quality and quantity. Li advises stopping at about 80% full, and Fung advises cutting sugar and refined foods.
- On diabetes medication or insulin? Change your eating pattern only with your doctor's help.
This is the short form. The full insight has every expert's reasoning, their own words and the sources.