Alcohol — what the science says

In a nutshell

Alcohol causes cancer — and no safe dose below which there would be no risk has been found.^1,2
“A glass for your health” did not hold up in the most careful analyses.³
Half a litre of beer has about 140 kcal from the alcohol alone; alcohol worsens sleep and slows muscle recovery.^4,5,6

1Cancer: no safe limit

Strong evidence 7 types of cancer The International Agency for Research on Cancer (IARC) classifies alcohol in Group 1 — proven carcinogens, alongside tobacco and asbestos. Alcohol causes cancer of the mouth, pharynx, larynx, oesophagus, liver, colon and rectum, and breast cancer in women.¹

In the body, alcohol is turned into acetaldehyde, which IARC also classifies as a carcinogen. So it does not matter whether you drink beer, wine or plum brandy — what counts is the amount of alcohol.¹

Strong evidence In 2023 the World Health Organization summed it up: no amount of alcohol is safe for health. Half of all alcohol-attributable cancers in Europe occur in people who drink “lightly” or “moderately” — less than 1.5 litres of wine, 3.5 litres of beer or 450 ml of spirits a week.²

2What about a glass for your health?

Older studies suggested that people who drink a little live longer than non-drinkers. The catch: the “non-drinkers” often included people who had quit because of illness — and they skewed the comparison.³

Moderate evidence 107 studies, 4.8 million people A large 2023 analysis corrected this error. People who drank little (up to about 24 g of alcohol a day — roughly one large beer) did not die any less often than lifelong non-drinkers. From 25 g a day the risk of death rose, and markedly so from 45 g.³

These are observational studies, so the exact numbers are uncertain. But they showed no protective effect of small doses.

3Calories you can't see

Fact 7 kcal per gram Alcohol has almost as much energy as fat (9 kcal/g) and more than sugar (4 kcal/g).⁴ Half a litre of 5% beer contains about 20 g of alcohol, so around 140 kcal from the alcohol alone — plus the sugars in the beer.

Tip: log your drinks in ForkRep like food. At the end of the week you will see how much there was.

4Sleep and muscles

Moderate evidence Alcohol helps you fall asleep faster, but the sleep is not better: at moderate and higher doses REM sleep decreases and the second half of the night is more restless.⁵

Weak evidence — a small study In an experiment with eight athletes, alcohol after training reduced muscle protein synthesis by 24% even when it was drunk with protein (by 37% with carbohydrates).⁶

5How Czechia compares

Data ~10 litres of pure alcohol a year for every inhabitant, children included — on average about 22 g a day, roughly a large beer for everyone every day. Czechia is among the countries with the highest consumption in Europe.⁷

What to take from this

If you don't drink, don't start for your health — no amount benefits health.
If you drink, less is better. Alcohol-free days and smaller glasses help.
Training days and the evening before are better without alcohol — for your muscles and your sleep.
Count the calories from drinks too. They are often the ones people forget.

Sources

Written on 7 Oct 2026, based on studies available at that date. Newer research may change the conclusions.

Secretan B. et al. (2009). A review of human carcinogens — Part E: tobacco, areca nut, alcohol, coal smoke, and salted fish. Lancet Oncology 10:1033–1034 (summary of IARC Monographs 100E). doi.org/10.1016/S1470-2045(09)70326-2
Anderson B. O. et al. (2023). Health and cancer risks associated with low levels of alcohol consumption. Lancet Public Health 8(1):e6–e7. doi.org/10.1016/S2468-2667(22)00317-6
Zhao J., Stockwell T. et al. (2023). Association between daily alcohol intake and risk of all-cause mortality: a systematic review and meta-analyses. JAMA Network Open 6(3):e236185. doi.org/10.1001/jamanetworkopen.2023.6185
Regulation (EU) No 1169/2011 on the provision of food information to consumers, Annex XIV (energy value of alcohol: 7 kcal/g). eur-lex.europa.eu
Ebrahim I. O., Shapiro C. M., Williams A. J., Fenwick P. B. (2013). Alcohol and sleep I: effects on normal sleep. Alcoholism: Clinical and Experimental Research 37(4):539–549. doi.org/10.1111/acer.12006
Parr E. B. et al. (2014). Alcohol ingestion impairs maximal post-exercise rates of myofibrillar protein synthesis following a single bout of concurrent training. PLoS ONE 9(2):e88384. doi.org/10.1371/journal.pone.0088384
Czech National Monitoring Centre for Drugs and Addiction (2023). Report on Alcohol in the Czech Republic 2023 — summary. drogy-info.cz

This is general information and does not replace a doctor. If you have problems with drinking, talk to your GP or an addiction service.