Q: How well do these operations work?
A: Over a year or two, weight-loss surgery can lead to loss of 50 percent to even 80 percent of the person's excess weight -- if they stick with a healthy diet and exercise. More important, research shows weight-loss surgeries can reverse Type 2 diabetes in patients who lose enough weight and keep it off. Gastric bypass causes the fastest weight loss, and stomach banding a more gradual loss.
But patients don't always benefit enough to justify surgery. The Agency for Healthcare Research and Quality cited reports that within five years, up to a third of stomach banding patients aren't maintaining their weight loss.
"You don't want somebody to always drink milkshakes because they're going to defeat the surgery over time," Ponce said.
Q: Is surgery safe?
A: Most are done laparoscopically -- through small incisions -- and Ponce's group says the risk of death is lower than for operations to remove a gall bladder or replace a hip. However, patients may suffer infection, blood clots, and broken or leaking stitches or staples.
After surgery, side effects can include vitamin deficiencies as food is digested differently, and vomiting as people learn to eat less and chew well. Gastric bypass patients also may suffer a complication that causes cramping and diarrhea, especially after eating sweets. The gastric band may slip out of place.
Q: Who's a candidate?
A: Generally, someone who is about 100 pounds overweight and has failed other attempts to lose. Doctors evaluate body mass index, a measure of weight for height. Candidates have a BMI of at least 40, or a BMI of 35 along with a weight-related health problem. For example, someone who is 5-foot-10-inches and weighs 279 pounds has a BMI of 40.
In 2011, The Food and Drug Administration relaxed the rules for stomach banding, allowing it for patients with a BMI as low as 30 who have a weight-related medical condition.
Weight-loss surgery can cost anywhere from $14,000 to $20,000; insurance tends to cover it for people who are sicker and more obese.