Woolford SJ, Sidell M, Li X, et al. - During the COVID-19 pandemic, weight gain was significant among Kaiser Permanente Southern California youths, particularly among the youngest children. If these findings are applicable to the United States, they point to an increase in pediatric obesity as a result of the pandemic.

• The cohort (n = 191 509) was racially and ethnically diverse (10.4% Asian and Pacific Islander, 50.4% Hispanic, 7.0% non-Hispanic Black, and 25.3% non-Hispanic White) with 49.6% females, the average age of 11.6 years (SD, 3.8 years), and a mean prepandemic BMI of 20.7 (SD, 5.4).

• During the COVID-19 pandemic, youths gained more weight than they did before the pandemic.

• With an increased BMI of 1.57, 5- through 11-year-olds had the highest shift in distance from the median BMI for age, compared with 0.91 for 12- through 15-year-olds and 0.48 for 16- through 17-year-olds.

• Adjusting for height, this translates to 2.30 kg more gain among 5- to 11-year-olds during the pandemic than during the reference period, 2.31 kg more gain among 12- to 15-year-olds, and 1.03 kg more gain among 16- to 17-year-olds during the pandemic than during the reference era.

• Overweight or obesity increased from 36.2% to 45.7% among 5- to 11-year-olds during the pandemic, an absolute increase of 8.7% and a relative increase of 23.8% compared with the reference period.

• The absolute increase in overweight or obesity among 12- to 15-year-olds was 5.2%, and 3.1% among 16- to 17-year-olds.

• Obesity was responsible for the majority of the increase among youths aged 5 to 11 years and 12 to 15 years.