Development of Body Weight and Waist Circumference Before, During and after the COVID-19 Pandemic - Population-Based Sample of 212,109 Young Men.

Introduction This study investigated population level changes in body weight and waist circumference before, during, and after the COVID-19 pandemic among young Finnish men with the average age of 20 years. Methods This retrospective study used data collected by the Finnish Defence Forces on body weight and waist circumference from 212,109 young men, with mean age of 20.0±1.1 years, commencing their compulsory military service between 2014 and 2023 (on average 21,211 individuals annually). Mean values, their confidence intervals (CI), proportion of overweight and obese individuals, and deciles were determined for each study year. Interrupted time-series analysis was used to compare trends before (2014-2020) and after (2021-2023) the onset of COVID-19. Moreover, we fitted linear and quadratic regression prediction models to the observed data to predict the development of body weight or waist circumference for the years 2024-2034. Results In year 2021, mean body weight was 0.72 kg (95% CI 0.35 to 1.09, p<0.001) and mean waist circumference 0.39 cm greater (95% CI 0.27 to 0.51, p<0.001) than the pre-pandemic level according to the interrupted time-series analysis. The values measured after the pandemic remained at this higher level. The proportion of abdominally overweight and obese individuals was greater after the pandemic (+1.72 percentage points for overweight, 95% CI 1.29 to 2.15, p<0.001 and +0.69 percentage points for obesity, 95% CI 0.23 to 1.15, p=0.003). Based on predictive models, the mean body weight and waist circumference of young Finnish men are likely to be greater over the next decade. Conclusion After the COVID-19 pandemic, the mean waist circumference, body weight, and proportion of young men with overweight or obesity were significantly greater compared with the values measured before the pandemic. The increasing prevalence of obesity and overweight are significant public health challenges and may contribute to a greater burden of non-communicable diseases in the future.