Nearly 5 million U.S. children and teens are severely obese, a near doubling over 20 years, and now according to new recommendations, some severely obese preteens should be considered for weight loss surgery.

The guidance was issued Sunday by the American Academy of Pediatrics; it’s based on a review of medical evidence, such as several studies showing that surgery in teens can result in marked weight loss lasting at least several years with few complications. In many cases, as The Associated Press reported, related health problems including diabetes and high blood pressure disappeared after surgery.

While most of those studies involved teens, one study included children younger than 12 and found no ill effects on growth, the policy said.

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Recent data show, as the AP reported, that pediatric obesity surgery rates have tripled in almost 20 years but still average fewer than 2,000 operations each year.

The academy’s recommendation said children and teens are generally eligible for surgery if their body mass index is 40 or higher, or at least 35 if they have related major health problems.

These criteria may vary by gender and age, said Dr. Sarah Armstrong, a Duke University pediatrics professor and the policy’s lead author.

They are similar to criteria for surgeons from the American Society for Metabolic and Bariatric Surgery.

A BMI of 30 and above is considered obese.

Most kids don’t get obesity surgery, mainly because most public and private health insurance doesn’t cover it or they live far from surgery centers, said Armstrong.

Costs can total at least $20,000.

It’s not a quick fix, she said. “It’s a lifelong decision with implications every single day for the rest of your life.”

Many obese kids already have developed related health problems including diabetes, high blood pressure, sleep apnea and liver disease.

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The condition of obesity affected 93.3 million adults in the country from 2015 to 2016, per the CDC.

The Associated Press contributed to this report.