LAUSR

Background Weight gain in adults is associated with an increased risk of obesity-related diseases and high healthcare costs. However, there have been limited studies on weight gain in Asians. This study investigated the prevalence, comorbidities, and associated factors of weight gain in the Korean population. Methods This is a cross-sectional study of Korean adults aged 19–64 years who participated in the Korea National Health and Nutritional Examination Survey 2016–2019. We used data from 15,514 adults (subjects 1) to analyze the prevalence of weight gain. Finally, after excluding adults with suspicious debilitating conditions among them, 11,477 adults (subjects 2) were used to analyze comorbidities and associated factors. Weight changes and lifestyle factors were assessed using a self-report questionnaire. We analyzed odds ratios and 95% confidence intervals using multivariable logistic regression analysis to examine factors associated with weight gain. Results The overall prevalence of weight gain was 25.7% in men and 31.3% in women and decreased significantly with age in both sexes. Weight gain of ≥ 6 kg was evident in 10.5% of men and 9.8% of women and was more pronounced with a higher baseline body mass index (BMI). Most metabolic comorbidities worsened the greater the weight gain. Young age was the strongest associated factor for weight gain. Other factors associated with weight gain were being unmarried, blue-collar job, lower income, and alcohol consumption in men; being married in women; smoking and skipping breakfast in both sexes. Conclusion Weight gain was much more pronounced in younger adults and at a higher baseline BMI in both sexes. Public education and health policies to prevent unnecessary weight gain should be strengthened by considering the associated harmful factors in Korean adults.