Body mass index and prevalence of metabolic syndrome among Korean adults before and after the COVID-19 outbreak: a retrospective longitudinal study

OBJECTIVES: Studies evaluating weight changes during the coronavirus disease 2019 (COVID-19) pandemic have yielded in-consistent results, and most of those studies were based on self-reported anthropometric measures. We investigated changes in body mass index (BMI), professionally measured waist circumference (WC), and metabolic syndrome components from before to during the pandemic in a sample of the adult population in Korea.METHODS: This retrospective study included 1,118 male and female (age >= 18 years) who underwent health checkups at a university medical center between January 1, 2016 and March 31, 2022. Changes in BMI, lifestyles, and metabolic syndrome components during the pandemic were analyzed using the paired t-test, McNemar test, generalized estimating equations, and repeated-measures analysis of variance.RESULTS: Changes in body weight, BMI, and body fat percentage during the pandemic were not clinically significant. How-ever, statistically significant results were found for decreased physical activity (p < 0.001) and WC (p < 0.001), and exacerbation of all metabolic syndrome components (except serum triglyceride levels). Moreover, the metabolic syndrome prevalence in-creased significantly from 20.2% to 31.2% during the pandemic (p < 0.001). The prevalence of abdominal obesity and high fasting blood glucose levels also significantly increased from 2019 to 2021.CONCLUSIONS: Metabolic syndrome, its components, and fat distribution worsened significantly after the implementation of social distancing and lockdowns, despite no clinically significant changes in body weight and BMI. Further studies on the post-pandemic period should investigate the long-term impact of social lockdowns on BMI and the prevalence of metabolic syndrome.