• Posted July 7, 2026

Weight Loss Surgery Increases Risk Of Alcoholism, Study Says

Weight loss surgery can be a lifesaver for people with severe obesity, but they will need to watch the booze from then on, a new study says.

People who undergo gastric bypass or gastric sleeve tend to absorb alcohol more rapidly afterward, researchers reported recently in the International Journal of Obesity.

As a result, they might be more prone to alcoholism, researchers said.

“Bariatric surgery can come with a price. Patients have a significantly higher risk of developing alcohol problems than if they did not undergo surgery,” lead investigator Magnus Strømmen said in a news release. He’s a research fellow at the Norwegian University of Science and Technology.

Bariatric surgeries reduce the volume in the stomach, leading patients to eat less and feel full faster. But this change in anatomy also affects what happens after someone starts drinking, researchers said.

"In a normal stomach, a significant part of the alcohol will be broken down and thus not pass into the bloodstream,” Strømmen said. “This is due to an enzyme that is secreted in the lining of the stomach. It is this protective mechanism that we deprive the patient of when we operate on the stomach. In addition, what you drink passes much faster into the intestine."

For the new study, researchers recruited 33 people slated to undergo bariatric surgery, and had them undergo alcohol stress tests with alcohol before surgery and at three, 12 and 36 months after their procedure.

The participants consumed precisely measured doses of screwdrivers — vodka and orange juice — during each test. Their blood alcohol levels were monitored.

Results showed that people became drunk faster and to a much greater extent even when drinking the same amount of alcohol. They also took longer to get sober.

"Our findings show that alcohol uptake almost doubles, both after gastric bypass and gastric sleeve,” Strømmen said. “Perhaps an even more dangerous finding, from a substance-abuse perspective, is that patients reach the maximum blood concentration in only half the time. These effects are lasting, probably lifelong."

A follow-up analysis of 17,800 Norwegian patients who underwent bariatric surgery from 2008 to 2018 revealed that those who underwent gastric bypass had a 69% higher risk of alcohol problems than those who received a gastric sleeve.

"The effects were more pronounced for people who had gastric bypass surgery, but that does not mean that the sleeve operation is harmless in terms of subsequent alcohol abuse," Strømmen said.

Strømmen counsels his bariatric patients that they need to be ready to say no when offered booze.

“They will suddenly be in social contexts where friends and surroundings expect you to drink as much as before the operation,” Strømmen said. “But your physiology has changed. That means you need to be more careful than before.”

Based on these results, people considering bariatric surgery should be warned of the changes in the way their bodies will process alcohol, he said.

“It is important that patients make their decision to undergo surgery on a genuinely informed basis,” Strømmen said. 

“It is not enough to say that their alcohol uptake will change," he said. "Patients should be educated about the mechanisms behind increased risk after surgery, and not least how to react differently to alcohol intoxication after surgery as a result of the sudden increase. This information can at best prevent patients from developing alcohol-related problems.”

Doctors also should quiz patients on their risk factors for substance abuse prior to surgery.

"I think most obesity clinics can get much better at their alcohol history, i.e. a thorough conversation about the patient's alcohol habits and any risk factors,” Strømmen said. “We need to get better at asking the right questions, and make a more precise assessment. But this also requires transparency from the patients. I believe that good patient education can make patients understand why it is important to be honest about these things.”

More information

Brigham and Women’s Hospital has more on alcohol after bariatric surgery.

SOURCE: Norwegian University of Science and Technology, news release, June 26, 2026