Weight loss, or bariatric, surgery was nine times more common in 2004 than in 1998 in the U.S. - 121,055 in 2004 - most of those operations were gastric bypass surgeries.

"This report shows that more Americans are turning to obesity surgery and that an increasing number of younger people are undergoing these procedures," says AHRQ Director Carolyn Clancy in an AHRQ news release.

"As the rate of obesity continues to climb, the health care system needs to be prepared for continued escalation in the rate of this surgery and its potential complications," Clancy says.

Bariatric surgery can have complications, but the report shows a drop in the hospital inpatient death rate. In 2004, 230 patients died in hospital stays in which bariatric surgery was performed, down nearly 80% from 1998.