Young-Soon Choi

(1) Background: During the coronavirus disease 2019 (COVID-19) pandemic, the prevalence of obesity or severe obesity has increased worldwide to the point that it has even been referred to as a new disease. However, the impacts of the pandemic on obesity or severe obesity remain unclear, thus requiring a thorough examination of the leading factors of obesity and severe obesity during this time. (2) Methods: The required dataset for this study was extracted from the eighth (2019–2020) Korea National Health and Nutrition Examination Survey (KNHNES). The survey’s data for 2019 and 2020 were analyzed to confirm the leading factors of obesity and severe obesity before and after the outbreak of COVID-19. The samples were weighted, and the data were analyzed using multiple logistic regression. (3) Results: In 2020, the prevalence of obesity and severe obesity in the Korean adult population aged 19 and over, compared with the normal weight group, showed significant increases of 2.5% and 1.4%, respectively, compared with those rates in 2019 (p < 0.05). The main variables affecting the obesity prevalence in Korean adults aged 19 and over in 2020 were gender, age, sitting time per day, and walking time per day, and the factors affecting severe obesity were gender and age. Meanwhile, the daily energy intake variable had no impact on the prevalence of obesity and severe obesity. (4) Conclusions: These findings will serve as a basis to help the present management directions and treatment approaches for individuals with obesity or severe obesity in the post-COVID-19 era.