NEW YORK — As more Americans turn to surgery to lose weight, more of them are also returning for a second operation because the first isn’t working.

Last year, an estimated 15 percent of the 252,000 obesity surgeries in the U.S. came after a previous surgery. That compares to 6 percent of the 158,000 surgeries in 2011, according to a surgeons’ group.

Weight-loss surgery has proven to be an effective way to treat obesity and related conditions like diabetes. Methods vary, but the operations generally shrink the stomach to limit how much people can eat without feeling sick.

Many people achieve significant weight loss but results aren’t assured: It’s still possible to overeat, restrictive devices can slip and stomachs can stretch back out and patients can regain weight over time.

That was the case for Kerrie Dutton, who had her first surgery four years ago.

At first, Dutton said she couldn’t eat much without feeling sick, as expected. She quickly dropped about 100 of her 320 pounds. Then gradually, her stomach started stretching, and she was able to eat more again.

“Going into the second year, I noticed that my weight was creeping up pretty quick,” said Dutton, 29, who lives on New York’s Long Island.

Dutton’s first operation was a newer procedure that cuts away part of the stomach and leaves a narrow sleevelike pouch. In October, she ended up converting to a more established surgery that reduces the stomach substantially more.

In the U.S., guidelines generally reserve weight-loss surgery for the severely obese — people with a body mass index of 40 or higher — or those with a BMI of 35 and over who have a related health problem like diabetes or high blood pressure.

About 4 in 10 American adults are obese and nearly 1 in 10 are severely obese, according to the latest survey by government researchers.

The American Society for Metabolic and Bariatric Surgery doesn’t provide a breakdown on which procedures are leading to subsequent operations. Dr. John Morton, a past president of the group and surgeon at the Yale School of Medicine, said it’s primarily patients who got an adjustable and removable band that restricts the size of the stomach. The band’s popularity in the U.S. has waned significantly.

ReShape Lifesciences, a medical device company that bought the Lap-Band system in 2018, said it doesn’t believe removal of its bands has been fueling second surgeries. Dr. Mark Watson, who does banding at UT Southwestern Medical Center in Dallas, said another surgery could be avoided with proper care of the band, which may need adjustment to work.

Contributing to the growing number of returning patients is the sleeve, which now accounts for 61 percent of U.S. procedures. Surgeons say many patients opt for the sleeve because it seems less complicated and less drastic than the bypass, which staples the stomach into a small pouch and shortens the intestinal tract.

Some surgeons are beginning to acknowledge the sleeve may not be the best option for some, such as the severely obese.

“It’s been too broadly applied,” said Dr. Stacy Brethauer, a Columbus, Ohio, surgeon and former president of the American Society for Metabolic and Bariatric Surgery.

Since the sleeve is relatively new, there isn’t strong data on how patients might fare over the long term, but Brethauer said surgeons have seen sleeve patients starting to return for a revision.

Prospective patients need to understand the options, surgeons say, since additional surgeries can increase the risk of complications. Dr. David Arterburn, a researcher who studies weight-loss procedures at Kaiser Permanente in Seattle, suggests people consult surgeons who are comfortable performing different procedures.

Dr. Neil Floch, a surgeon in Norwalk, Conn., said the right procedure will depend on the person’s situation: “It’s an individualized decision as to which surgery a particular person should have to get the best result.”

After the sleeve, the most common procedure is the traditional gastric bypass. It’s considered more effective partly because it also limits how much food is digested. Generally, both are considered safe and performed laparoscopically, or through small incisions.

The need for another surgery doesn’t necessarily mean patients regret their decisions. Some say they got what they believed was the best option for them at the time.

Others like Anita Saah, a 45-year-old Rockville, Md., resident, may have taken a different route in hindsight.

In 2018, Saah opted for the sleeve because it seemed less risky than the bypass. She lost weight immediately but suffered severe dehydration afterward and was vomiting bile, likely because of her previous acid reflux issues.

In September, she had another surgery, this time a bypass. She hasn’t had further complications and only wishes she understood how serious the acid reflux could become.