Association Between Anthropometric Indices and Vitamin D Levels: Results From the Yazd Health Study

Background Obesity and overweight are widespread health problems affecting many populations. Some studies have shown an inverse association between obesity and vitamin D levels. This study aims to explore the connection between vitamin D levels and various body measurements in Iranian men and women. Methods This cross-sectional study used data from the Yazd Health Study. The final sample included 1116 men and women aged 20-70. We measured the following anthropometric indices: Body Mass Index (BMI), Waist-to-Hip Ratio, Waist-to-Height Ratio (WHR), conicity index, Body Roundness Index (BRI), body shape index, Abdominal Volume Index (AVI), Body Fat Percentage (BF%), Body Muscle Percentage (BM%), and visceral fat level. We fitted multiple linear regression models in three steps to adjust for confounders. Results In men, after adjusting for age, physical activity, hypertension, and diabetes mellitus, vitamin D deficiency showed a positive and nearly borderline significant association with WHtR (β = 0.027, 95% CI: 0.005; 0.048), BRI (β = 0.583, 95% CI: 0.136; 1.030), AVI (β = 1.761, 95% CI: 0.372; 3.150), and BF% (β = 3.614, 95% CI: 0.926; 6.303), and a negative association with BM% (β = -1.978, 95% CI: -3.655; -0.300). The associations of BRI and BF% with vitamin D deficiency remained borderline significant after further adjustment for other potential confounders. In women, vitamin D levels were not significantly associated with any of the anthropometric indices. Discussion Vitamin D levels differentially influence body composition across genders, highlighting potential sex-specific metabolic mechanisms of obesity and vitamin D status, and the need for targeted prevention and intervention strategies. Conclusion Vitamin D shows inverse associations with certain body indices in men, highlighting the importance of obesity vulnerability and the need for broader mechanistic studies.