Fasting Tracker

Quick answers

Does alcohol break a fast?

Yes, and it does more than add calories. Keep any drink inside your eating window, with food

What's in a drink

Calculated from USDA FoodData Central values.
DrinkServingCalories
Beer, regular355 ml (12 oz)About 150
Red wine150 ml (5 oz)About 125
Spirits, 40% (gin, rum, vodka, whisky)44 ml (1.5 oz)About 100
MixersA 355 ml canTonic adds about 124 more; soda water adds none

Why alcohol puts fat burning on hold

Key study

Alcohol came first

  • Metabolic study
  • 8 healthy men
  • 24 g of alcohol

After a drink with 24 g of alcohol, a little less than two beers, the release of fat from fat tissue fell by 53% and the body's fat burning by 73%. Most of the alcohol was turned into acetate, which the body burned instead.

Siler et al., Am J Clin Nutr 1999

Your body treats alcohol as a fuel to clear first. So a drink during a fast does more than add calories: it pauses the very thing many people fast for.

Drinking on an empty stomach

Alcohol hits harder without food. In a Swedish study, 10 men drank the same amount either after an overnight fast or straight after breakfast. On an empty stomach, their peak blood alcohol was about 55% higher, they felt more drunk, and it took about two hours longer to clear 4.

Alcohol also stops your liver from releasing and making glucose. Without food, especially when your stores are low after a long fast, or with diabetes medication such as sulfonylureas, it can bring on low blood sugar 5.

And your sleep

A drink may help you fall asleep, but it disrupts the second half of the night, and moderate and higher doses cut REM sleep 6. Poor sleep makes the next day's fast harder: after two short nights, healthy young men felt 24% hungrier 7.

If you drink

  1. Drink with a meal inside your eating window, not to break a fast.
  2. Keep it early, a few hours before bed.
  3. Alternate each drink with a glass of water.
  4. Choose soda water over tonic, juice or sugary mixers.
  5. Start your next fast when your window closes, as usual.

Sources

  1. Regulation (EU) No 1169/2011 on the provision of food information to consumers, Annex XIV: conversion factors for the calculation of energy. www.legislation.gov.uk/eur/2011/1169/annex/XIV
  2. U.S. Department of Agriculture, Agricultural Research Service. FoodData Central: Alcoholic beverage, beer, regular, all (FDC ID 168746); wine, table, red (FDC ID 173190); distilled, all (gin, rum, vodka, whiskey) 80 proof (FDC ID 174815). SR Legacy. fdc.nal.usda.gov/
  3. Siler SQ, Neese RA, Hellerstein MK. De novo lipogenesis, lipid kinetics, and whole-body lipid balances in humans after acute alcohol consumption. Am J Clin Nutr. 1999;70(5):928-36. doi.org/10.1093/ajcn/70.5.928
  4. Jones AW, Jönsson KA. Food-induced lowering of blood-ethanol profiles and increased rate of elimination immediately after a meal. J Forensic Sci. 1994;39(4):1084-93. pubmed.ncbi.nlm.nih.gov/8064267/
  5. van de Wiel A. Diabetes mellitus and alcohol. Diabetes Metab Res Rev. 2004;20(4):263-7. doi.org/10.1002/dmrr.492
  6. Ebrahim IO, Shapiro CM, Williams AJ, Fenwick PB. Alcohol and sleep I: effects on normal sleep. Alcohol Clin Exp Res. 2013;37(4):539-49. doi.org/10.1111/acer.12006
  7. Spiegel K, Tasali E, Penev P, et al. Brief communication: Sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Intern Med. 2004;141(11):846-50. doi.org/10.7326/0003-4819-141-11-200412070-00008

A note on health

Fasting Tracker is designed for general wellness and is not a medical device. Fasting is not right for everyone. If you are pregnant, diabetic, have a history of eating disorders or take medication, talk to your doctor first, and before any extended fast.