**Background:** Osteoporosis is a disease characterized by low bone mass and deterioration of bone microarchitecture, leading to increased fracture risk. Postmenopausal osteoporosis is common among women aged ≥50 years, with bone mineral density (BMD) measurement being the most important diagnostic test. The relationship between obesity and osteoporosis has been extensively studied, with most research suggesting a protective effect of obesity against osteoporosis. However, the regional distribution of adipose tissue matters—visceral adipose tissue releases inflammatory factors that may increase bone resorption, while subcutaneous adipose tissue may have protective effects through hormones like leptin. The visceral adiposity index (VAI), calculated from BMI, waist circumference (WC), triglyceride (TG), and HDL-cholesterol levels, reflects visceral fat distribution and insulin resistance. This study aimed to investigate the relationship between BMD and VAI levels in postmenopausal women, as no prior study had examined this association.
**Methods:** The study was conducted at the Division of Endocrinology and Metabolism, Konya Training and Research Hospital between January and June 2017. A total of 120 postmenopausal women aged >50 and <70 years who were menopausal for at least 1 year were included. Based on DXA lumbar spine T-scores, participants were divided into three age- and BMI-matched groups: 40 with normal BMD, 40 with osteopenia, and 40 with osteoporosis. Exclusion criteria included age <50 or >70 years, premature or surgical menopause, diseases causing secondary osteoporosis, malabsorption conditions, prior osteoporosis treatment, hormone replacement therapy, lipid-lowering medications within 6 months, active infections, rheumatologic diseases, cancers, chronic infections, liver and kidney failure, smoking, and alcohol consumption. Blood samples were collected after 12 hours of fasting to measure TG, HDL-cholesterol, glucose, and insulin. BMD was measured using DXA (Hologic QDR 4500W). VAI was calculated using the formula: (WC/[36.58 + (1.89 × BMI)]) × (1.52/HDL [mmol/L] × TG/0.81 [mmol/L]). HOMA-IR was calculated as (fasting glucose [mg/dL] × fasting insulin [μU/mL])/405. Statistical analyses included Kolmogorov-Smirnov test, Student's t-test, Mann-Whitney U test, Spearman correlation, and regression analysis.
**Key Results:** No significant differences were found between the three groups in age, time since menopause, height, weight, BMI, SBP, DBP, insulin, glucose, HDL-cholesterol, or HOMA-IR levels. Waist circumference was significantly higher in the normal BMD group compared to both osteopenic (p=0.018) and osteoporotic groups (p<0.001), and higher in the osteopenic group compared to the osteoporotic group (p=0.003). TG levels were significantly higher in the normal BMD group compared to the osteoporotic group (p=0.005). VAI levels were significantly higher in women with normal BMD compared to those with osteoporosis (p=0.002). Correlation analysis revealed a positive correlation between DXA lumbar spine T-scores and both WC (r=0.442, p<0.001) and VAI (r=0.199, p=0.030), and a negative correlation with age (r=-0.181, p=0.047). Logistic regression analysis showed that each 1-year increase in time since menopause caused a 0.096 decrease in lumbar spine T-score (p=0.004), while each 1-cm increase in WC led to a 0.037 increase in T-score (p<0.001).
**Clinical Implications:** This is the first study to investigate the relationship between VAI and BMD. The findings suggest that higher VAI and WC levels are associated with higher BMD and may have a protective effect against osteoporosis in postmenopausal women. The positive correlation between VAI and lumbar spine T-scores supports the concept that visceral adiposity, as reflected by VAI, may protect against bone loss. However, the study has limitations including the lack of direct measurement of visceral fat via DXA, and the absence of assessment of nutritional habits and exercise status. The authors note that further studies with larger populations are needed to clarify the relationship between VAI and BMD.