What Breaks a Fast?
Know exactly what keeps you in — and kicks you out of — a fasted state.
Understanding what breaks a fast helps you make smarter choices during your fasting window.
What definitely breaks a fast:
- Any food — even a small snack counts as breaking your fast
- Caloric beverages — juice, smoothies, milk, cream in coffee, alcohol
- Supplements with calories — gummy vitamins, protein shakes, BCAAs
- Chewing gum with sugar (sugar-free gum in small amounts is generally fine)
Gray areas:
- Medications — Most medications are fine to take while fasting. Some should be taken with food; ask your doctor.
- Vitamins and supplements — Capsule-based vitamins with no added sugar are generally fine.
- Very small amounts of fat (like a splash of cream) — Technically breaks a clean fast but has minimal impact on metabolic markers like insulin. This depends on your IF goals.
- Apple cider vinegar — Generally considered fine in small amounts diluted in water.
Strict vs flexible fasting:
If your goal is autophagy (cellular cleanup), you need a very clean fast — only water, black coffee, or plain tea. If your goal is weight loss or general health, a splash of cream in coffee is unlikely to derail your results.
Keep it simple: if it has calories, it breaks your fast.