CHICAGO (AP) — The most common type of obesity surgery may increase patients' chances for alcohol abuse, according to the largest study to demonstrate a potential link.

Patients who had gastric bypass surgery faced double the risk for excessive drinking, compared with those who had a less drastic weight-loss operation.

Gastric bypass surgery shrinks the stomach's size and attaches it to a lower portion of the intestine. That limits food intake and the body's ability to absorb calories. Researchers believe it also changes how the body digests and metabolizes alcohol; some people who've had the surgery say they feel alcohol's effects much more quickly, after drinking less, than before the operation. The study suggests that may lead to problem drinking.