Who should consider gastric bypass?

Don't even think about it if you're just overweight, not severely obese.

Although there is growing acceptance in the medical community that surgery is an appropriate last-ditch treatment for severe obesity, many experts caution that no one with a body mass index (BMI) of less than 40, or less than 35 with a life-threatening condition, should consider it.

Anyone contemplating surgery also should be highly motivated to make permanent dietary changes, be willing to stick to a rigid and off-putting eating regimen for months -- or years -- and have tried less-invasive methods of weight loss. Children and adolescents should not have surgery because the operation has only been studied in adults, according to the National Institutes of Health.

Here are some other suggestions for potential candidates, culled from the NIH and the American Society for Bariatric Surgery:

-- Carefully consider the risks. Gastric bypass is major abdominal surgery and involves rearrangement of the gastrointestinal tract. The death rate from the procedure is about 3 per 1,000 patients; serious complications include blood clots, internal hemorrhage, stroke and infection from an abdominal leak. Although the operation can be undone, reversal is considered to be more dangerous than the original procedure. After reversal, it is likely that the digestive tract will not function as it did before bypass surgery.

-- Insist on experience. Choose a surgeon who is board-certified and has done hundreds of Roux-en-Y gastric bypass or vertical banded gastroplasty operations. Ask about the doctor's complication and re-operation rates. Ten to 20 percent of patients require additional surgery to correct complications. A rate above 20 percent is a red flag.

-- Be prepared for more surgery. Gallstones are common and many patients may need to have their gallbladders removed. Bypass operations also result in the formation of scar tissue, which can cause a bowel obstruction that may occur years after surgery. This is a potentially fatal complication that must be treated promptly. Patients who lose a lot of weight often need plastic surgery to remove folds of hanging skin. Insurance companies typically consider this to be a cosmetic procedure and most won't pay for it.

-- Get ready to take vitamins -- lots of them. Anemia, osteoporosis and other nutritional deficiencies are common after surgery because the duodenum, the portion of the intestine that absorbs iron and calcium, is bypassed. Many patients also suffer hair loss. These problems may be offset by taking extra calcium and vitamins and eating enough protein.

-- Do some research.