Exploring the Association Between Older Adults' Body Mass Index and Their Fall Experience, Chronic Diseases, and Exercise Frequency: Evidence from Korea.

: Many older adults face health challenges, such as physical and functional decline, which increase the risk of hospitalization and dependence. As the global population ages, it is necessary to consider the health of older adults to avoid additional health burdens while improving their quality of life. This study aimed to explore body mass index (BMI) as a factor associated with health in older adults in South Korea. Accordingly, this study investigated the associations between the BMI of older Korean adults and exercise frequency (days per week), fall experience, and the presence of chronic diseases. : Data from 10,014 older adults who participated in the 2023 Korean National Survey on Older Adults conducted by the Ministry of Health and Welfare were analyzed. Analyses included statistical frequency, chi-square tests, and multivariate logistic regression. : Underweight older adults had a higher likelihood of falling. Among those who were underweight, the odds ratio (OR) for falls was 2.052 (95% confidence interval [CI]: 1.349-3.121; = 0.001). Underweight individuals were also less likely to engage in regular exercise. In contrast, both normal-weight and overweight individuals were more likely to participate in frequent exercise. Among those who were underweight, the ORs for exercising for 3-4 and ≥5 days were 0.612 (95% CI: 0.388-0.966; = 0.035) and 0.721 (95% CI: 0.527-0.987; = 0.041), respectively. Among those who were normal weight, the ORs for exercising for 1-2, 3-4, and ≥5 days were 1.286 (95% CI: 1.020-1.621; = 0.033), 1.226 (95% CI: 1.055-1.424; = 0.008), and 1.307 (95% CI: 1.167-1.464; < 0.001), respectively. Among overweight individuals, the ORs for exercising for 1-2, 3-4, and ≥5 days were 1.275 (95% CI: 1.008-1.613; = 0.043), 1.297 (95% CI: 1.114-1.509; = 0.001), and 1.172 (95% CI: 1.042-1.318; = 0.008), respectively. Older adults with obesity had a higher likelihood of having chronic diseases. Among those who were underweight, the ORs for one, two, three, and four diseases were 0.420 (95% CI: 0.268-0.658; < 0.001), 0.335 (95% CI: 0.220-0.509; < 0.001), 0.266 (95% CI: 0.167-0.422; < 0.001), and 0.392 (95% CI: 0.254-0.606; < 0.001), respectively. Among those with normal weight, the ORs for two, three, and four diseases were 0.686 (95% CI: 0.579-0.813; < 0.001), 0.606 (95% CI: 0.505-0.727; < 0.001), and 0.609 (95% CI: 0.505-0.735; < 0.001), respectively, compared to those with obesity. Among those who were overweight, the ORs for two, three, and four diseases were 0.800 (95% CI: 0.671-0.953; = 0.013), 0.781 (95% CI: 0.649-0.941; = 0.009), and 0.686 (95% CI: 0.564-0.835; < 0.001), respectively, compared to those with obesity. : Weight is a key factor in promoting healthy aging in older adults. It is necessary to reduce the risk of falls in underweight individuals and prevent chronic diseases in those who are obese. Regular physical activity supports interventions that address these risks. Older adults should be supported and engage in consistent exercise tailored to their physical abilities and individual characteristics to maintain or improve their health and well-being later in life.