Association Between Body Mass Index (BMI), Vitamin D, and Testosterone Levels

Introduction Obesity is measured scientifically by calculating body mass index (BMI). Body mass index in men is linked to various hormonal imbalances. This study aims to observe the relationships between BMI, vitamin D, and testosterone levels in patients attending the outpatient clinic at Hayatabad Medical Complex, Peshawar, Pakistan. Methods This observational cross-sectional study involved 272 patients, presenting to the medical outpatient department from January 1^st, 2023, to December 31^st, 2023. Body mass index, serum vitamin D, and testosterone levels were measured for each participant. Body mass index was categorized into normal, overweight, and obese. Statistical analysis was calculated, including descriptive statistics, logistic regression, and correlation analysis to evaluate associations between these variables. Results The mean BMI of the participants was 25.82 ± 7.88 kg/m². A significant inverse correlation was observed between BMI and vitamin D levels (r = -0.79, p < 0.001) and between BMI and testosterone levels (r = -0.87, p < 0.001). A positive correlation was found between vitamin D and testosterone levels (r = 0.87, p < 0.001). Logistic regression analysis revealed that higher BMI in the range of overweight or above was associated with a 2.5-fold increase in the likelihood of vitamin D deficiency (odds ratio (OR) = 2.50, 95% CI = 1.8-3.5, p < 0.001) and a 3.1-fold increase in the likelihood of low testosterone levels (OR = 3.10, 95% CI = 2.2-4.3, p < 0.001). Conclusion In this study, higher BMI is significantly associated with lower vitamin D and testosterone levels. These findings suggest that addressing obesity could help mitigate hormonal imbalances, such as vitamin D deficiency and low testosterone, which are linked to metabolic health risks. It can also be hypothesized that obesity can be a risk factor for vitamin D and testosterone deficiency.