Changes in lifestyle, adiposity, and cardiometabolic markers among young adults in Sweden during the COVID-19 pandemic

{"Background": "Obesity is a major public health challenge globally, increasing the risk of cardiovascular disease, type 2 diabetes, and cancer. In Sweden, over half of adults and nearly one in three young adults have overweight or obesity. The COVID-19 pandemic and associated restrictions disrupted daily life, with studies reporting decreased physical activity, increased sedentary time, and weight gain. However, few studies have examined changes in body composition (fat vs. lean mass) or cardiometabolic markers in young adults, and results vary by country due to differing restrictions. Sweden kept society relatively open without a formal lockdown, making it a unique setting to study pandemic-related health changes. This study aimed to investigate changes in lifestyle, adiposity (BMI, body fat percentage, trunk fat), blood pressure, and pulse among young adults in Sweden during the pandemic, and to identify determinants of these changes.", "Methods": "The study included 1,004 participants from the population-based BAMSE birth cohort (originally 4,089 newborns from Stockholm). Participants underwent clinical examinations at two time points: before the pandemic (December 2016\u2013May 2019; mean age 22.6 years) and during the pandemic (October 2020\u2013June 2021; mean age 25.7 years; median time span 3.2 years). Trained nurses measured height, weight, body composition via bioelectric impedance analysis (Tanita MC 780), and resting blood pressure and pulse (Omron HBP-1300, mean of three measurements). BMI was calculated and categorized per WHO standards. Body fat percentage was classified as high using sex-specific cutoffs (\u226533% for females, \u226520% for males). High blood pressure was defined as \u2265140/90 mmHg. Lifestyle changes during the pandemic were assessed via a questionnaire (phase 3, October 2021\u2013February 2022) asking about changes in physical activity, sedentary time, diet, alcohol, stress, sleep, and health (5-point Likert scale collapsed to decreased, unchanged, increased). Sociodemographic data (parental occupation, parental birth country, education, occupation, smoking, snuff use) were collected from earlier follow-ups. Pregnant women (n=18) were excluded. Non-parametric tests (Wilcoxon signed-rank, McNemar's, Kruskal-Wallis) were used for paired and unpaired comparisons. Mutually adjusted quantile regression models examined associations between sociodemographic/lifestyle factors and median changes in BMI and body fat percentage.", "Key Results": "All adiposity measures increased significantly. In females, median weight increased by 1.2 kg, BMI by 0.5 kg/m\u00b2, body fat percentage by 0.8% (all p<0.001). In males, median weight increased by 2.1 kg, BMI by 0.6 kg/m\u00b2, body fat percentage by 1.5% (all p<0.001). Trunk fat percentage also increased in both sexes. The prevalence of overweight/obesity in males rose from 23.2% to 37.1% (p<0.001). In females, obesity prevalence increased from 3.2% to 7.1% (p<0.001), while overweight prevalence did not change significantly. The proportion with high body fat percentage increased from 13.9% to 16.8% in females and from 23.2% to 37.1% in males. Blood pressure increased significantly: the proportion with high blood pressure rose from 3.1% to 8.4% in females (p<0.001) and from 18.2% to 33.2% in males (p<0.001). Pulse also increased in both sexes. In adjusted quantile regression models, male sex was associated with 0.83% higher median increase in body fat percentage (p=0.02). Having a parent born outside Scandinavia was associated with 0.76 kg/m\u00b2 higher median BMI increase (p=0.001) and 0.93% higher body fat increase (p=0.05). Pre-pandemic obesity was associated with 1.45 kg/m\u00b2 higher median BMI increase (p=0.002), while underweight was associated with 1.57% higher body fat increase (p=0.03). Self-reported lifestyle changes: 38.6% decreased physical activity (41.7% females, 33.4% males, p=0.04), 57.8% increased sedentary time, 44.1% reduced alcohol intake, and 37.4% increased stress. Females who decreased physical activity had a median body fat increase of 1.10%, while those who increased physical activity had a median decrease of 0.10%. Similar patterns were observed for sedentary time and dietary habits.", "Clinical Implications": "This study provides evidence that the COVID-19 pandemic period was associated with significant adverse changes in adiposity and cardiometabolic markers among Swedish young adults, despite relatively mild restrictions. The increases in BMI, body fat percentage, and particularly blood pressure (with 33% of males classified as having high blood pressure during the pandemic) are concerning for future cardiovascular risk. The findings highlight that vulnerable groups\u2014males, individuals with non-Scandinavian ethnicity, and those with underweight or obesity at baseline\u2014experienced greater adverse changes. Self-reported lifestyle changes, especially reduced physical activity and increased sedentary time, were directly linked to adiposity increases. These results underscore the need for targeted public health measures to promote healthy lifestyles and prevent obesity and hypertension in young adults, particularly in populations disproportionately affected by the pandemic. The study's limitations include the inability to definitively attribute changes to the pandemic versus aging, potential selection bias (only ~25% of the original cohort), and reliance on self-reported lifestyle changes collected late in the pandemic, which may underestimate early-pandemic effects."}