Body Composition Metrics as Predictors of Vitamin D Status in Obese Adults: A Clinical Investigation

Obesity represents a major global health issue and is frequently linked to micronutrient deficiencies, particularly vitamin D deficiency. The interplay between body composition—especially fat mass and bone mass—and serum vitamin D levels among obese individuals remains an important area of investigation. This cross-sectional observational study involved 79 obese adult participants classified by body mass index (BMI). Body composition, including fat and bone mass, was assessed using Bioelectrical Impedance Analysis (BIA MC-980), while serum vitamin D levels were measured using the ELISA method. Statistical analyses were performed to examine the relationship between body composition and vitamin D status. The results revealed a significant inverse association between body fat mass and serum vitamin D concentration (p < 0.001), suggesting that increased adiposity is related to lower circulating vitamin D. Conversely, bone mass demonstrated a significant positive association with serum vitamin D levels (coefficient = 8.23; p = 0.003) across the total sample. These findings indicate that fat mass exerts a stronger influence on vitamin D status among obese adults, potentially due to sequestration of the vitamin in adipose tissue. Meanwhile, bone mass appears positively correlated with vitamin D levels, underscoring its role in skeletal health. Further longitudinal and mechanistic studies are necessary to clarify causal relationships and the physiological pathways underlying these associations.