PASADENA, Calif.—A Kaiser Permanente study of nearly 200,000 Southern California children found that children gained excess weight during the COVID-19 pandemic, especially those between the ages of 5 and 11, according to results released Sept. 27.

“When we compared the weight gain among children from 2019 to 2020, we found that there was more weight gained during the pandemic for youths of all ages,” senior author Corinna Koebnick of the Kaiser Permanente Southern California Department of Research & Evaluation said in a statement.

“And this weight gain fell disproportionally on the youngest children. On average, 5- to 11-year-olds gained 5 extra pounds, while 16- to 17-year-olds gained 2 extra pounds. The result was an almost 9 percent increase in the youngest children falling into the categories of being overweight and obese.

“As children go back to school it will be important to focus on health and physical activity to help children not carry unwanted extra weight into adulthood.”

To determine the weight gains, researchers used electronic health records of 191,509 members of Kaiser Permanente in Southern California from March 1, 2019, to January 31, 2021. The study found an increase of body weight and prevalence of obesity in children 5 to 11 years old during the course of the pandemic.

The study results were published in the Journal of the American Medical Association.