Does apple cider vinegar break a fast?
Tiny calories, but not a strict clean fast
3 kcal per tbsp
Maybe - use caution. A tablespoon of apple cider vinegar is very low calorie, but it is acidic and still counts as more than plain water.
The calorie load is tiny, so weight-loss fasting is usually not affected; strict clean fasting should keep the window to water, coffee, tea, and zero-sugar electrolytes.
USDA-linked nutrition data lists cider vinegar at about 3 kcal per tablespoon, with negligible carbohydrate and no protein or fat.
Base tier: 60/100 for "Use caution". Item adjustment: +16 points for calories, nutrient signal, product variability, and safety caution. Final Fast Score: 76/100.
Dilute it heavily and avoid it if it worsens reflux, nausea, or tooth sensitivity.
Do not use vinegar as a medication substitute, and be careful if you have reflux, ulcers, kidney disease, or diabetes medication changes.
The Fast Score is an editorial estimate of clean-fast strictness, not medical advice. Goals vary — if you fast for glucose, appetite, or medical reasons, follow your clinician.