Does beer break a fast?

A 355 ml (12 fl oz) can of regular beer has about 150 kcal. A US pint (473 ml) is about 200 kcal. A UK pint (568 ml) of 5% beer is up to about 220 kcal, and stronger beers go higher. Alcohol carries about 7 kcal per gram. A can of 5% beer holds about 14 g of alcohol, so about 100 of its 150 kcal come from the alcohol. The rest comes from carbohydrate and other parts of the malted grain.

On the four goals this site uses to sort answers, beer breaks a fast for weight loss, blood sugar, autophagy and gut rest. A can is three times the common 50-calorie rule of thumb, which is not an official limit. The carbohydrate in beer raises blood glucose, and the drink has to be absorbed and processed, so no goal stays fasted. Alcohol never gets a safe verdict on this site.

Alcohol also slows fat burning after the drink. One study gave 8 men 24 g of alcohol, a little under two cans of 5% beer. Their fat burning fell by 73% for some hours. The study was small, so the evidence is early.

Drinking at the end of a fast, before you eat, makes the alcohol hit harder. Food slows the absorption of alcohol and can lower the peak level in the body by about a third. If you drink, have it with a meal in your eating window. If you take insulin or some other diabetes medicines, alcohol without food raises the risk of low blood sugar. Take your medicines as prescribed and ask your doctor how drinking fits with fasting.

If you want to cut down or stop, a doctor or pharmacist can help. No amount of alcohol is free of risk. WHO Europe puts it this way, "No level of alcohol consumption is safe for our health."