Does Apple Cider Vinegar Break a Fast?

Quick answer: No, not for intermittent fasting for weight loss. One tablespoon of apple cider vinegar (ACV) has about 3 calories and roughly 0.1 g of carbs, far too little to matter. It is not allowed on a strict water-only fast, and it is not allowed before a fasting blood test, where labs usually ask for plain water only. Always dilute it.

Try it yourself: On a 16:8 plan with meals from 11 AM to 7 PM, a tablespoon of ACV stirred into a large glass of water at 9 AM adds about 3 calories, so your fast keeps going. If ACV upsets your stomach, move it to your 11 AM meal instead. Set up your own window in the intermittent fasting calculator.

Calories and Carbs in Apple Cider Vinegar

Values below are based on USDA FoodData Central figures for cider vinegar (21 calories and 0.93 g carbs per 100 g).

For comparison, a cup of plain black coffee has about 2 calories. A spoonful of ACV is in the same “too small to count” range. See how many calories break a fast for the bigger picture.

Does ACV Break a Fast? It Depends on Your Goal

“Fasting” means different things to different people, so the honest answer changes with the goal.

Weight-loss intermittent fasting

For most people using 14:10 or 16:8 to eat less, ACV in water is fine. The calories are tiny, and it can make a plain glass of water feel more like a “drink.”

Ketosis

Ketosis depends mainly on keeping carbs very low. A tablespoon of ACV has about a tenth of a gram, so it is very unlikely to affect ketone levels on its own. ACV gummies and “detox” drinks are a different story, since many add sugar.

Autophagy

Autophagy is the body’s cell-recycling process, and fasting is thought to boost it. Most of what’s known comes from lab and animal research, and there is no simple test to measure it in people. Nobody has studied whether a spoonful of ACV changes it, so any claim either way is a guess.

Fasting blood tests

MedlinePlus advises plain water only during the 8 to 12 hours before a fasting blood test, and says other drinks can affect results. Skip ACV until after your blood draw, and follow your lab’s instructions.

Does ACV Help You Lose Weight While Fasting?

The evidence is thin. In one Japanese trial, adults with obesity who drank a beverage containing 15 or 30 mL of vinegar daily for 12 weeks lost slightly more weight and visceral fat than a placebo group (Kondo et al., 2009). Mayo Clinic notes that research hasn’t proven ACV helps people slim down and that studies are mostly small. Treat ACV as an optional extra, not a fat-loss tool. A steady calorie deficit matters far more.

How to Take ACV Safely

ACV is very acidic. A few simple habits lower the risk of problems:

• Always dilute it. Never take it straight. Mix it into a large glass of water.
• Protect your teeth. In a small 8-week trial, adults who drank 2 tablespoons of vinegar in a cup of water twice daily had an 18% rise in tooth-wear scores, while the control group didn’t (Anderson et al., 2021). Rinse with plain water afterward, and don’t brush right away.
• Watch your throat. Mayo Clinic says ACV may irritate the throat when taken often or in large amounts, and tablets can get stuck and cause lasting pain.
• Reflux and heartburn: Harvard Health notes there is no published research on ACV for heartburn and no data on its safety for that use. If you get reflux, an acidic drink on an empty stomach may not be a good fit.
• Check your medicines. Mayo Clinic warns ACV may lower potassium when combined with certain drugs, including diuretics (common blood pressure pills) and insulin, as well as licorice and horsetail supplements.

ACV, Fasting and Women Over 40

If you take a diuretic for blood pressure or use insulin, ask your doctor or pharmacist before making ACV a daily habit, because of the potassium concern above. Tooth enamel doesn’t grow back, so the rinse-and-dilute habit matters more with every year.

If fasting isn’t moving the scale in perimenopause, ACV is unlikely to be the missing piece. Read why intermittent fasting may not be working in menopause for the factors that usually matter more.

Frequently Asked Questions

Can I drink apple cider vinegar during intermittent fasting?

Yes. One to two tablespoons diluted in water adds only about 3 to 6 calories, so it fits a weight-loss fasting window.

Does apple cider vinegar kick you out of ketosis?

Very unlikely. A tablespoon has only about 0.1 g of carbs. Sweetened ACV drinks or gummies are a different matter.

Will apple cider vinegar stop autophagy?

No one knows. There’s no human research on ACV and autophagy, and autophagy is hard to measure in people.

Is it okay to take apple cider vinegar on an empty stomach?

Some people do, but it can irritate the throat and stomach. If you notice burning or nausea, take it with a meal instead, and always dilute it.

Do ACV gummies break a fast?

Often yes. Many gummies contain sugar, so check the label for calories and carbs.

Does lemon water break a fast?

A squeeze of lemon adds very few calories. See does lemon water break a fast.

Related Tools

• Intermittent Fasting Calculator
• Calorie Deficit Calculator
• Does Diet Soda Break a Fast?

This article is for general information only and is not medical advice. Read our Medical Disclaimer.

Sources

• USDA FoodData Central: Vinegar, cider (FDC 173469) — https://fdc.nal.usda.gov/
• Kondo T, et al. Vinegar intake reduces body weight, body fat mass, and serum triglyceride levels in obese Japanese subjects. Biosci Biotechnol Biochem. 2009 — https://pubmed.ncbi.nlm.nih.gov/19661687/
• Anderson S, et al. Evidence that daily vinegar ingestion may contribute to erosive tooth wear in adults. J Med Food. 2021 — https://pubmed.ncbi.nlm.nih.gov/33297831/
• Mayo Clinic: Apple cider vinegar for weight loss — https://www.mayoclinic.org/health/apple-cider-vinegar-for-weight-loss/AN01816
• MedlinePlus (NIH): Fasting for a Blood Test — https://medlineplus.gov/lab-tests/fasting-for-a-blood-test