Updated December 08, 2016

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By Amanda Gardner

MONDAY, June 18, 2012 ( — Certain patients who undergo weight-loss surgery may have a heightened risk of developing a drinking problem, but the risk is only apparent two years after the procedure and only with one type of surgery.

A new study, published today on the website of the Journal of the American Medical Association, examined the drinking habits of almost 2,000 obese adults before and after bariatric surgery.

Before the surgery, 7.6% of the study participants met the criteria for an alcohol-use disorder. One year after the procedure that number had actually declined slightly, to 7.3%, but by the end of the second year it had risen to 9.6%—a 57% increase from the pre-surgery rate.

The risk of developing an alcohol-use disorder was twice as high among patients undergoing Roux-en-Y gastric bypass surgery—which accounted for 70% of the procedures in the study—than among patients undergoing laparoscopic gastric banding (also known as lap band surgery). But the risk wasn't appreciably higher with other types of weight-loss surgery, such as gastric banding or gastric sleeve surgery.

The researchers can only speculate why the uptick in alcohol-use disorders was restricted to Roux-en-Y patients and took two years to become apparent. The most likely culprit is an increased sensitivity to alcohol, coupled with a gradual return to pre-surgery drinking habits, says lead author Wendy King, Ph.D., an assistant professor of epidemiology at the University of Pittsburgh Graduate School of Public Health.

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Roux-en Y bypass involves reducing the size of the stomach and bypassing part of the small intestine, both of which cause alcohol to pass into the bloodstream more quickly, King explains.

In addition, Roux-en-Y patients are advised not to drink for 30 minutes after eating, which increases the likelihood that they'll consume alcohol on an empty or near-empty stomach. "The switch to drinking without food could also impact sensitivity," says King, who presented her findings today at the annual meeting of the American Society for Metabolic and Bariatric Surgery, in San Diego.

Replacing one addiction with another (in this case, food for alcohol), a phenomenon known as addiction swapping, seems not to have played a role here. Binge eaters, who are comparable in many ways to binge drinkers, were no more likely than other people to develop an alcohol-use disorder, King says.

Other factors were associated with increased risk, however. Men, younger people, smokers, regular drinkers (including moderate drinkers), recreational drug users, and people who feel like they don't belong—a marker of poor social support—were all at increased risk relative to their peers.

Overall, 1 in 8 study participants reported drinking at least three alcoholic drinks per typical drinking occasion two years post-surgery.

"That level of drinking, independent of any relationship to alcohol-use disorder, may have negative implications for weight loss, for liver health, and vitamin and mineral absorption," King says. "Those who undergo Roux-en-Y surgery already have compromised absorption, and heavy drinking could make it worse."

The study had some limitations. It shows only an association, not cause and effect, and the participants may have underreported their alcohol consumption, especially since people with alcohol-use disorders are generally advised against bariatric surgery.

Candidates for weight-loss surgery should be aware of the risk of alcohol problems, but the new findings by themselves shouldn't dissuade anyone from considering the surgery, King says.

"This is the best treatment we have today for severe obesity," King says. "With any medical procedure, there are risks and benefits."