Alcohol belly? Gut health expert reveals EXACTLY why booze makes you poop differently

It’s well known that drinking too much can lead to a headache, fatigue and an upset stomach, but why does knocking back one too many have you racing to the bathroom the next day?

Now, an expert has revealed how alcohol wrecks havoc on your body and digestion. 

Vincent Ho, an associate professor of gastroenterology at Western Sydney University, said alcohol messes with the way your body processes food, particularly how long it takes for food to travel through the gut.

Alcohol can accelerate the movement of food through the stomach and intestines, causing diarrhea. It also reduces the absorption of nutrients and people who indulge in sugary alcoholic beverages are more likely to suffer in the bathroom the next day. 

Beverages such as beer and wine speed up food transit, but vodka and whisky slow it down, creating a sense of fullness or discomfort.

The above graph shows how long it takes the body to return to baseline following a weekend of drinking

However, not all alcohol is created equal and some may actually have the opposite effect. 

Beverages such as beer and wine speed up food transit, but vodka and whisky slow it down, creating a sense of fullness or discomfort. 

A study in rats showed those exposed to high doses of alcohol experienced delays in food processing in the small bowel. This could suggest that people who engage in an episode of binge drinking – as opposed to repeated heavy drinking – may actually experience constipation more than diarrhea. 

In a 2022 study, 500 people recorded their bowel movements and had their stools collected for analysis. Based on self-reporting surveys, researchers found people who reported a heavy drinking episode had harder, firmer bowel movements. 

Researchers believed the brief period of heavy drinking led to a delay in food being processed in the gut – and the longer food stays in the intestines, the more water is absorbed from the stool back into the body, leading to dry and hard poop. 

Not everyone experienced this, however. In people with pre existing digestive issues, such as irritable bowel syndrome, binge drinking led to diarrhea, nausea and abdominal pain.  

And chronic alcohol use can even have longterm effects on your gut as it has been linked to lactose intolerance, overgrowth of small bowel bacteria and reduced nutrition absorption. 

If you find yourself frequently experiencing digestive issues, the best thing you can do, Mr Ho said, is to limit alcohol intake and pay attention to what type of alcohol impacts you the most. 

If you experience diarrhea after a night out, it can be helpful to avoid mixing alcohol with caffeinated drinks, which are known to cause bowel problems. 

If constipation is the issue, staying hydrated is important. Mr Ho recommends drinking water even before you start drinking alcohol. 

Also, drinking water in between alcoholic beverages and before you go to bed can also help avoid discomfort. 

Eating protein and fiber-rich foods can be beneficial. Having food in your stomach before drinking helps cushion the effects alcohol has on the gut lining.  

Mr Ho said changes in bowel movements after drinking alcohol are usually short-lived and harmless and resolve themselves in a few days. 

However, if symptoms persist beyond several days after drinking, it could be a sign of a digestive health condition.