Outbreak of Severe Obesity and Metabolic Complications in Children and Adolescents Using the Korea National School Health Examination (KNSHE) From 2017 to 2021

Background: This study aimed to estimate the prevalence of obesity in school children by severity and to assess the coronavirus disease 2019 (COVID-19) pandemic’s impact on changes in the prevalence of obesity. In addition, the prevalence of obesity-related metabolic complications was calculated. Methods: We used data from 390,580 school-aged children in the 2017–2021 Korea National School Health Examination to estimate the prevalence of obesity and assess secular trends in prevalence. We estimated the prevalence of metabolic complications in overweight and obese students with serological data and assessed their association with the degree of obesity, which was classified as overweight, obesity, and severe obesity per the criteria of the American Academy of Pediatrics. Results: In 2021, the prevalence of overweight, obesity, and severe obesity among school children was 12.5%, 17.6%, and 4.9%, respectively, for boys and 10.8%, 11.9%, and 2.9%, respectively, for girls, and these values have been increasing significantly since 2017. Compared with the pre-COVID-19 period, the increase in the prevalence of obesity and severe obesity was remarkable, especially in elementary school students. The linear relationship between the prevalence of metabolic complications and the degree of obesity was evident in high school students. In elementary school students, similar relationships were found with nonalcoholic fatty liver disease and high blood pressure. Conclusion: The severity of obesity in school-age children (especially younger children) is worsening, and this may predict an increase in the prevalence of related metabolic complications. To prevent long-term complications, it is essential to expand health screening programs.