Regional Implications of the COVID-19 Pandemic on Childhood Obesity Prevalence, Denver, Colorado, 2019–2022

<b><i>Background:</i></b> During the early COVID-19 pandemic, many US youths experience rapid excess weight gain and increase in BMI and obesity prevalence. We leveraged longitudinal electronic health records from three health care organizations in metropolitan Denver, Colorado, to assess COVID-19 pandemic effects on BMI and obesity prevalence. <b><i>Methods:</i></b> Using a retrospective cohort of 55,429 children aged 2-19 years, each with ≥3 BMI measurements during 2019-2022, we used mixed-effects regression models to estimate rates of change in BMI and obesity prevalence during prepandemic, early pandemic (March-December 2020), and two later pandemic periods (2021, 2022). <b><i>Results:</i></b> The average rate of BMI gain was nearly 70% higher during early pandemic compared to prepandemic [rate ratio (RR): 1.68 (95% confidence interval {CI}: 1.60-1.76)] but attenuated substantially as the pandemic continued [RR: 0.37 (95% CI: 0.34-0.40) for 2021 vs. early pandemic]. This coincided with changes in estimated obesity prevalence from 16% to 17% prepandemic to 21% by December 2020% to 20% by December 2022. School-aged children 6-13 years, those with prepandemic healthy weight, and Hispanic and non-Hispanic Black children had the most pronounced BMI increases in early pandemic. <b><i>Conclusions:</i></b> Although rates of BMI gain leveled out from early pandemic increases, obesity prevalence in health care-seeking youths in metropolitan Denver remained substantially higher in 2022 than prepandemic, particularly in certain subgroups. Opportunities exist to strengthen institutions and programs that support healthy eating, physical activity, and maintenance of a healthy weight. This work underscores the value of regional surveillance systems to monitor disease trends and inform local efforts to support children's health.