Changes in Lifestyle Behaviors and Cardiovascular Disease Risk Factors Before and After the COVID-19 Pandemic: A Nationally Representative Study from Korea

<b>Background:</b> The COVID-19 pandemic has substantially altered lifestyle behaviors, potentially affecting cardiovascular health. This study examined changes in lifestyle behaviors-specifically physical activity, smoking, and alcohol consumption-and cardiovascular disease (CVD) risk factors before and after the pandemic using nationally representative data from Korea. <b>Methods:</b> Data were obtained from the Korea National Health and Nutrition Examination Survey (KNHANES) from 2016 to 2023. Weighted analyses were conducted to ensure national representativeness. Descriptive and inferential statistics (<i>t</i>-tests, ANOVA, and correlation analyses) were used to compare health behaviors and CVD risk factors between pre-pandemic (2016-2019) and post-pandemic (2020-2023) periods. <b>Results:</b> Adherence to aerobic physical activity declined from 45.5% before the pandemic to 42.1% after the pandemic, and resistance exercise participation also decreased (<i>p</i> < 0.05). Average sedentary time increased from 8.1 ± 3.5 to 8.7 ± 3.4 h/day. Body mass index (BMI) increased from 23.9 ± 3.7 to 24.1 ± 3.5 kg/m², and triglyceride levels similarly increased (<i>p</i> < 0.05). In contrast, smoking prevalence decreased from 17.2% to 16.5%, and the average number of cigarettes smoked per day declined from 13 to 11-12. Alcohol intake per occasion also decreased significantly after the pandemic (<i>p</i> < 0.05). However, lipid indicators such as total cholesterol and LDL-C tended to be higher in the post-pandemic period, indicating unfavorable changes rather than improvement. Correlation analyses further showed that heavy drinking was associated with higher BMI, glucose, and triglyceride levels, whereas moderate drinking showed more favorable metabolic profiles. <b>Conclusions:</b> The COVID-19 pandemic exerted mixed effects on lifestyle behaviors and cardiovascular risk factors among Korean adults. While reductions in physical activity and increases in sedentary time may elevate long-term health risks, concurrent decreases in smoking and alcohol intake could have mitigated some negative outcomes. Nevertheless, adverse changes in lipid profiles-including increases in LDL-C, total cholesterol, and triglycerides-suggest that metabolic health worsened overall after the pandemic. These findings underscore the urgent need for tailored public health strategies to promote balanced lifestyle behaviors and mitigate cardiovascular risks in the post-pandemic era.