Weight-loss surgery, once a last resort for extremely overweight people, may soon become an option for those who are less heavy. An advisory committee to the Food and Drug Administration will consider Friday a request by Allergan, the pharmaceutical company, to significantly lower how obese someone must be to qualify for surgery using the company's Lap-Band device, which restricts intake to the stomach. On Wednesday, the FDA acknowledged that a new study by the company showed that people in the proposed range of obesity who had the band experienced 'statistically significant decreases in all measures of weight loss.' If the agency approves the change, the number of Americans eligible for the lap-band operation could easily double, ensuring more sales for Allergan and probably more insurance coverage for such operations. The proposed change, sought at a time when the U.S. obesity epidemic seems intractable, still leaves some people uneasy, in part because of side effects and failure rates. In addition, long-term weight reduction is hard to maintain. 'You're talking about millions and millions of people who would meet these criteria,' said Dr. George Blackburn, associate director of the division of nutrition at Harvard Medical School. 'Let's make sure by the most rigorous research that this is safe and effective.' A new generation of diet pills has failed to gain federal approval, limiting options for overweight Americans, and Allergan and other companies are betting that surgery will become more of a frontline option rather than a last resort. 'It would be kind of ironic if people have access to surgery and not medical therapies, where they can go from Weight Watchers to surgery and have nothing in between,' said Dr. Louis J. Aronne, an obesity expert at Weill Cornell Medical College. 'But it appears it may be the way it will be in the near future.' Doctors have already started to operate on extremely heavy teenagers, and some experts are recasting weight-loss procedures, known as bariatric surgery, as metabolic surgery, saying that it might be justified to treat diabetes, even in people who are barely obese or not obese. Gastric banding involves placing an inflatable silicone ring around the upper part of the stomach, which limits food consumption and makes one feel full faster. Current guidelines say weight loss surgery is appropriate for people who have failed to lose weight through diet and exercise and have a body mass index, or BMI, of 40 and above, or 35 and above if a person has at least one serious health problem, like diabetes or high blood pressure, that is tied to obesity. Allergan wants to lower the threshold for the lap-band to a BMI of 35 with no associated health problems and to 30 with such problems. For instance, a person who is 5-feet-6 inches and has diabetes would have to weigh 216 pounds to qualify now. Under the proposed lower threshold, that person could weigh 30 pounds less, or 186 pounds. Federal statistics suggest that nearly 20 percent of the adult population has a BMI between 30 and 35, more than double the population above 35. Probably half or more of the people between 30 and 35 have some associated health condition. Bariatric surgeons and some obesity experts say that surgery has proven to be the only way many people can lose a lot of weight and keep it off, and some cite a Swedish study suggesting that it prolonged lives. And, they say, the operations have become safer since the obesity thresholds were first set in 1991 in a meeting organized by the National Institutes of Health. 'The whole risk-benefit ratio is completely different than it was back then,' said Dr. Marc Bessler, chief of the division of minimally invasive and bariatric surgery at Columbia University. Banding is a less radical operation than the main alternative, the gastric bypass. It is also reversible and costs less -- from $12,000 to more than $20,000, compared with $20,000 to more than $30,000 for a bypass. Banding also leads to a weight loss of about 20 percent on average, though, less than that of bypass. Bypass has been the preferred operation in the United States, although Allergan executives said on a recent call with investors that banding now has about 50 percent market share. Within the banding market, Allergan's lap-band has about 70 percent market share, according to the company, with the rest belonging to the Realize Band sold by Ethicon Endo-Surgery, a division of Johnson & Johnson. Allergan's band was approved in 2001. To win approval of the lower threshold, Allergan sponsored a study in which 149 of these less obese people had the band implanted. About 80 percent of the participants achieved the goal of losing at least 30 percent of their excess weight, meaning the amount by which they were overweight, after one year. About 70 percent of patients experienced a side effect, like vomiting or pain. The FDA indicated Wednesday that it had questions about how meaningful the weight loss was and whether the results of the study would be applicable to people other than the white women who made up a large portion of the participants. Some doctors are dropping the band, in part because some older studies suggest that up to one-third of patients eventually have the band removed because of side effects or ineffective weight loss. While about 1 in 1,000 patients die within 30 days of surgery, a survey of members of the bariatric surgery society suggested that deaths occurring later are under-reported. 'Before they start putting the Lap-Band on patients who are 50 pounds overweight, the public has to be made aware of how dangerous this is,' said Stephanie Quatinetz, a New York attorney whose daughter, Rebecca, died at age 27 in August 2009, two months after getting lap-band surgery. One factor that is moving some experts to advocate surgery for lower body mass index levels is its effectiveness in resolving diabetes, hypertension and some other ills associated with obesity. 'There are dramatic metabolic effects that in many cases go well beyond the weight loss effects,' said Dr. Lee M. Kaplan, director of the weight center at Massachusetts General Hospital. He said that while it was once thought that surgery worked mainly by mechanically restricting how much one can eat, it is becoming clear that gastric bypass, at least, has effects on hormones. Some experts say body mass index does not adequately measure risk of health problems. For instance, Asians tend to get diabetes at a lower BMI than whites. 'The BMI limitation of 35/40, set in the period when the major objective of the operations was weight control, is no longer the primary appropriate guideline for the selection of candidates for bariatric surgery,' Dr. Walter J. Pories, a surgeon, and colleagues wrote in the journal Obesity earlier this year. Pories will be a member of the FDA advisory committee Friday. Allergan, known mostly for its Botox product, which is approved for cosmetic and medical ailments like chronic migraines, wants to reverse slowing sales of the lap-band that the company attributes to the weak economy. In the first nine months of this year, sales of its obesity products, mostly lap-band, fell 4 percent, to $182.4 million. Even if Allergan's application is approved, perhaps a small fraction of the new candidates are likely to opt for surgery because many people avoid operations. 'I don't think it's enough to overwhelm the health care system,' said Dr. Bruce Wolfe, president of American Society for Metabolic and Bariatric Surgery, whose executive council unanimously endorsed Allergan's proposal. 'That's not happening with the people who are heavier and need it even more.' The society says that 220,000 bariatric surgeries of all kinds were performed in the United States last year. That is more than twice as many as in 2003 but represents a small fraction of the potential pool. Still, some less obese patients do want the surgery. Some online discussion boards tell of people who purposely gained weight to qualify, and some messages give advice to others on wearing hidden weights. Rashida Brown says she wants surgery to help control her diabetes, high cholesterol and hypertension. But her insurer has refused to pay twice in the past few years. At the time, Brown, who is 5-feet-7, weighed 195 to 220 pounds, putting her index below 35. 'I am willing to bet there are quite a few people in the same category as myself -- just waiting,' said Brown, 53, a clinical social worker from Boston. She may still have to wait, now that she weighs 175 pounds -- putting her below even the proposed lower threshold. 