Title of the manuscript: Relationship between Body Mass Index and Bone Mineral Density in Postmenopausal Women

Objective: To investigate the relationship between body weight, body mass index (BMI) and bone mineral density (BMD) in natural postmenopausal women. Methods: : A total of 149 natural postmenopausal patients admitted from October 2020 to April 2022 were selected and divided into control group (88 cases with BMI<24.0 kg/m2) and Observation group (61 cases with BMI≥24kg/m 2 ). All patients were scanned using dual-energy X-ray absorptiometry, standard BMD scans were performed on the lumbar spine (L1, L2, L3, L4, L1-L4) and the hip (whole hip, femoral neck, trochanter, and femoral shaft). Pearson correlation or correlation coefficient test was used to analyze the relationship between BMI, body weight and BMD at different sites and to compare the differences in BMD at different sites between the two groups. Results: : There were no significant differences in age, menopause age and height between the two groups, but the body weight of the observation group was significantly higher than that of the control group, the difference was statistically significant (P < 0.01). BMD of L1, L2, L3, L4, L1-L4, hip, neck of femur, trochanter and femoral shaft in observation group were significantly higher than those in control group, with statistical significance (P < 0.01). BMI and body weight was positively correlated with L1, L2, L3, L4, L1-L4, femoral neck and total hip BMD, with statistical significance (P < 0.01). Conclusion: Postmenopausal women with higher BMI and weight may reduce the risk of osteoporosis, which can reduce the risk of fragility fracture.