Wang X, et al. - Seventy-one obese Chinese subjects (34 males, age 31.70 ± 9.61 years and 37 females, age 32.80 ± 11.45 years) after laparoscopic sleeve gastrectomy (LSG) were studied for the changes in bone mineral density (BMD), bone metabolic parameters, and serum bone morphogenetic protein 4 (BMP4) levels. Outcomes suggested differences in the effect of LSG on BMD between genders, decreasing significantly in females while remaining unchanged in males. Furthermore, in obese Chinese female patients, decreased BMP4 levels may partly account for the diminished BMD after LSG.