Multifactorial Determinants of Body Composition in the Korean Older Adults: Using Data from the 2022–2023 National Health and Nutrition Examination Survey

<b>Background/Objectives</b>: Sarcopenia, abdominal obesity, and sarcopenic obesity are prevalent and clinically significant in older adults, each shaped by diverse biopsychosocial factors. However, integrative analyses using nationally representative data remain limited in Korea. <b>Methods</b>: We analyzed 2118 adults aged ≥65 years from the 2022-2023 Korea National Health and Nutrition Examination Survey (KNHANES). Body composition was classified into sarcopenia, abdominal obesity, and sarcopenic obesity. Guided by Engel's Biopsychosocial Model, we examined biological (e.g., sex, chronic disease, nutrition, exercise), psychological (e.g., stress, sleep, self-rated health), and social (e.g., income, education, living status) variables. Complex-sample multinomial logistic regression identified condition-specific associations. <b>Results</b>: Prevalence rates were 18.2% for sarcopenia, 41.0% for abdominal obesity, and 3.4% for sarcopenic obesity. Eating alone and a lack of resistance exercise were common risk factors across all three conditions. Sarcopenia was associated with male sex, insufficient dietary intake, alcohol consumption, poor self-rated health, and low household income. Abdominal obesity was linked to recent weight gain, hypertension, diabetes, prolonged sedentary time, perceived obesity, and low educational attainment. Sarcopenic obesity was associated with male sex, diabetes, elevated hs-CRP, perceived stress, poor self-rated health, and economic inactivity. <b>Conclusions</b>: Body composition abnormalities among older Korean adults are influenced by complex, condition-specific interactions across biological, psychological, and social domains. These findings emphasize the significance of adopting an integrative perspective that considers physical, psychological, and social health components when addressing age-related body composition issues.