Association Between Normal-Weight Obesity and Bone Mineral Content in Chinese Adolescents Aged 12–18 Years Old: A Population-Based Cross-Sectional Study

Objective: The effects of normal-weight obesity, which is defined as having a high level of body fat despite a normal body mass index, on the health of bones in adolescents are very limited. Hence, the purpose of this investigation was to explore the relationship between normal-weight obesity and bone mineral content (BMC) among Chinese adolescents. Design and method: This cross-sectional study included 1,960 children and adolescents aged between 12 and 18 years who were selected from schools in Yinchuan city by stratified cluster random sampling. Subjects were divided into three groups according to body mass index (BMI) and percentage of body fat (PBF), as follows: normal-weight non-obesity(NWNO), normal-weight obesity (NWO), and obesity (OB). Results: The NWNO, NWO, and OB phenotypes in boys were 69.9%, 8.8%, and 21.3%, respectively, and were 35.3%, 48.6%, and 16.1% in girls, respectively. The OB phenotypes had higher BMC than the NWNO phenotype (all p < 0.05), and the NWO phenotype with BMC was significantly lower than NWNO group in boys (p < 0.05). We discovered a significant positive correlation between BMC and the NWO (OR = 1.62, 95% CI = 1.19–2.20), while negative correlation was found between BMC and OW phenotypes in neither boys nor girls. Conclusions: Normal-weight obesity adolescents had higher BMC, and there existed sex differences in the effect of PBF on BMC among them.