Associations Between Body Composition and Bone Mineral Density in Adults with Metabolic Syndrome: A DEXA-Based Cross-sectional Study

Background and Objective: Body composition is increasingly recognized as an important factor associated with bone health; however, evidence focusing on individuals with metabolic syndrome (MetS) remains limited, particularly in Southeast Asian populations. Methods: This cross-sectional study included 128 adults with MetS recruited from two medical centers in Vietnam between October 2017 and September 2024. All participants underwent dual-energy X-ray absorptiometry (DEXA) to assess regional body composition and bone mineral density (BMD). Associations between lean mass, fat distribution, and BMD across multiple skeletal sites were evaluated using Pearson correlation analysis. Results: Lean mass indices, including Lean Mass Index (LMI) and Appendicular Skeletal Muscle Index (ASMI), were positively associated with BMD across multiple skeletal sites, with the strongest associations observed in the appendicular skeleton and whole body (r = 0.17 - 0.73, P < 0.001). In contrast, central adiposity, reflected by the android-to-gynoid (A/G) fat ratio and regional fat percentages, showed inverse associations with BMD, particularly at the spine and long bones (r = -0.20 to -0.29, P < 0.05). Conclusions: In adults with MetS, lean mass was positively associated with BMD, whereas central adiposity showed inverse associations with skeletal health. These findings highlight the importance of body composition, beyond BMI alone, in the assessment of bone health in this high-risk population. DEXA-based body composition assessment may provide clinically relevant information to support patient evaluation.