NEW YORK — A new study ties the COVID-19 pandemic to an “alarming” increase in obesity in U.S. children and teenagers.

Childhood obesity has been increasing for decades, but the new work suggests an acceleration last year — especially in those who already were obese when the pandemic started.

The results signal a “profound increase in weight gain for kids” and are “substantial and alarming,” said one of the study's authors, Dr. Alyson Goodman of the Centers for Disease Control and Prevention.

It's also a sign of a vicious cycle. The pandemic appears to be worsening the nation's longstanding obesity epidemic, and obesity can put people at risk for more severe illness after coronavirus infection.

The CDC on Thursday released the study, which is the largest yet to look at obesity trends during the pandemic.

It found:

—An estimated 22% of children and teens were obese last August, up from 19% a year earlier.

—Before the pandemic, children who were a healthy weight were gaining an average of 3.4 pounds a year. That rose to 5.4 pounds during the pandemic.

—For kids who were moderately obese, expected weight gain rose from 6.5 pounds a year before the pandemic to 12 pounds after the pandemic began.

—For severely obese kids, expected annual weight gain went from 8.8 pounds to 14.6 pounds.

The rate of obesity increased most dramatically in kids ages 6 to 11, who are more dependent on their parents and may have been more affected when schools suspended in-person classes, the researchers said.

The research was based on a review of the medical records of more than 432,000 kids and teens, ages of 2 to 19, who were weighed and measured at least twice before the pandemic and at least once early in the pandemic.

Some limitations: It only included children who got care before and during the pandemic, the researchers said. And it also did not offer a look at how obesity trends may have differed between racial and ethnic groups.

Earlier this week, the CDC said the number of states in which at least 35% of residents are obese increased last year by four.

Delaware, Iowa, Ohio and Texas joined the list. In 2019, there were 12 states — Alabama, Arkansas, Indiana, Kansas, Kentucky, Louisiana, Michigan, Mississippi, Oklahoma, South Carolina, Tennessee, and West Virginia.

Those results was based on surveys where adults described their own height and weight, and are not as accurate as medical records.