CHICAGO, Illinois (AP) -- Obesity surgery, which is fast becoming a popular way to battle the nation's weight crisis, may be a lot riskier than most patients realize.New research found a higher-than-expected risk of death in the year after surgery, even among young patients."It's a reality check for those patients who are considering these operations," said University of Washington surgeon Dr. David Flum, lead author of a Medicare study that analyzed the risks.The findings appear in Wednesday's Journal of the American Medical Association.Some previous studies of people in their 30s to their 50s -- the most common ages for obesity surgery -- found death rates well under 1 percent.But in a study of 16,155 Medicare patients who underwent obesity surgery, more than 5 percent of men and nearly 3 percent of women aged 35 to 44 were dead within a year. And slightly higher rates were found in patients 45 to 54.Among patients 65 to 74, nearly 13 percent of men and about 6 percent of women died. In patients 75 and older, half of the men and 40 percent of the women died.There are several types of operations to lose weight, most generally involving surgically shrinking the stomach and usually restricted to "morbidly" obese people more than 100 pounds overweight.Those patients often have medical problems brought on by their girth, including heart trouble, diabetes and breathing difficulties -- problems which obesity surgery can sometimes resolve but which can also contribute to making the surgery risky.Patients studied underwent surgery between 1997 and 2002."This is a major operation in a high-risk population. "When you do a complicated operation in a complicated population, we should expect to see adverse outcomes" occasionally, Flume said.Dr. Neil Hutcher, president of the American Society for Bariatric Surgery, said that Medicare patients are probably sicker than the general U.S. population and that complication rates have declined as surgeons' expertise has increased.But Flum argued that some previous research showing lower risks came from "reports from the best surgeons reporting their best results," while the new study is more of a real-world look.A JAMA editorial said even if Medicare patients do face higher risks, they should not be denied obesity surgery."These patients may also represent the potential greatest benefit associated with major lasting weight loss given their associated disease burden," the editorial said.The surgery may be lifesaving when done on the right patients, by experienced surgeons, the editorial said.The study offered no breakdown on causes of death, but obesity surgery's potentially deadly complications can include malnutrition, infection and bowel and gallbladder problems. Also, surgery in general can be a deadly shock to the system, especially in older patients.The American Society for Bariatric Surgery predicts obesity surgery will be performed more than 150,000 times this year in the United States. That is more than 10 times the number in 1998, according to a second JAMA study. The increase parallels a surge in the portion of U.S. adults who are at least 100 pounds overweight, from about 1 in 200 in 1986 to 1 in 50 in 2000, that study said.Flum said the new study suggests that in many cases, obesity surgery may not be right for an older person "who already has the burden of 60 years of obesity on their heart" and other organs.Medicare covers obesity surgery if it is recommended to treat related conditions such as diabetes and heart problems. The government is considering whether to cover surgery to treat obesity alone.Medicare is for younger Americans with disabilities and for patients 65 and older. Flum said most of the patients he studied were under 65 and probably qualified for Medicare because of obesity-related ills, including heart and joint problems.Flum's study lumped together data on different operations, but the most common U.S. obesity surgery, gastric bypass, involves creating an egg-size pouch in the upper stomach and attaching it to a section of intestine.Researchers said one reason men may have higher post-surgery death rates is that they tend to wait longer than women to seek medical help and may be sicker at surgery.Hutcher said patients should seek experienced surgeons, should be thoroughly evaluated before and after surgery, and should receive long-term follow-up care.Most patients "will receive a good outcome," Hutcher said. "A good outcome does not mean there's no risk for complications or mortality."Copyright 2005 The Associated Press. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed.