Body Mass Index in Children Before, During, and After the COVID-19 Pandemic
Authors' conclusion
In this cross-sectional study of changes in iso-BMI in children in Denmark, prevalence of overweight and obesity increased during COVID-19. The prevalence of overweight declined after COVID-19, but the prevalence of obesity remained increased among first-grade children. Additionally, the prevalence of underweight increased in sixth-grade children after COVID-19. These findings highlight differences among children of varying ages and BMI classes.
Study context
- Population
- First- and sixth-grade children in Denmark with anthropometric data in the Children's Database, March 11, 2019, to January 31, 2024268,761 first-grade, 158,174 sixth-grade
- Exposure
- During and after COVID-19 vs before COVID-19
- Outcome
- Changes in age- and sex-adjusted body mass index (BMI) (iso-BMI); Adjusted prevalence ratios (aPRs) of iso-BMI categories (underweight, normal weight, overweight, obesity), adjusted for sex, household income and parental education
Methodological detailsnationwide, population-based, registry-based, Data analyzed in March 2024
- Nationwide
- Population-based
- Registry-based
- Data analyzed in March 2024
Main finding
As reported in the abstract
Prevalence of iso-BMI categories vs pre-COVID-19
Each group vs before COVID-19Adjusted prevalence ratio (95% CI)
During COVID-19underweight, first grade
0.76(0.71–0.83)
After COVID-19underweight, sixth grade
1.15(1.06–1.24)
After COVID-19overweight, first grade
0.97(0.94–0.99)
After COVID-19overweight, sixth grade
0.95(0.93–0.98)
After COVID-19obesity, first grade
1.12(1.07–1.18)
Observational data: associations, not effects.
Original publication
Body Mass Index in Children Before, During, and After the COVID-19 Pandemic. JAMA Netw Open. Published 1 July 2025. doi:10.
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