BOSTON -- Gastric bypass surgery, the procedure that reduces the size of the stomach and induces significant weight loss, is growing in popularity.

The number of surgeries in Massachusetts has tripled since 2000, according to officials.

But when the surgery is successful, NewsCenter 5's Liz Brunner reported, patients are often left with a new problem, one that not all insurance carriers cover.

Fifteen months ago, Sue Fosdick had gastric bypass surgery as a last-ditch attempt to drop weight and be healthier. It worked and she lost almost 200 pounds.

"I've lost more than half my body weight, and now I have hanging skin everywhere," said Fosdick.

While her insurer, Blue Cross Blue Shield, paid for her weight loss surgery, they will not pay for the skin to be removed. For Fosdick, who also has multiple sclerosis, it's much more than a cosmetic issue.

"That excess weighs my arms down and causes pain," she said.

Surgeon Mike Tarnoff said just 20 percent of patients who feel they need skin removal following gastric bypass actually get it because insurers don't deem it medically necessary.

"It's rare that a patient comes in because they want it for cosmetic purposes. The ones that come in and ask for this are generally coming in because they're somewhat disabled from it," said Tarnoff, of the Tufts New England Medical Center.

Some question whether insurers should pick up a $40,000 or $50,000 plastic surgery bill given rising health care premiums.

"If we spend more and more money on expensive procedures that have low payoff, that means fewer dollars are available to take care of all of us when we're really sick," said Alan Sager, of the Boston University School of Public Health.

Fosdick said she's already saving the insurance company plenty of money. Because of her weight loss, she isn't likely to get high blood pressure, diabetes, heart failure or have other obesity-related diseases.

"Your insurance company, after you've saved them millions of dollars, says, 'No, we're not going to cover this. No, this is a luxury. No, you can't have this done.' We're back in the dark ages," Fosdick said.

Blue Cross would not comment on this case, citing privacy laws. But a spokesman said the insurer is a leader in providing health insurance coverage for weight loss surgery and that members have the right to appeal any coverage that is denied.