The association between overweight and obesity on bone mineral density in 12 to 15 years old adolescents in China

Overweight/obesity can influence bone mineral accretion, but the conclusions are not consistent. We aimed to examine the association between bone mineral density (BMD) levels and body mass index (BMI) in 12 to 15 years old adolescents. We performed a cross-sectional study including 8365 adolescents. BMD was evaluated using a quantitative ultrasound device. Z scores for BMI were evaluated using World Health Organization references. Logistic regression models were performed to evaluate the association between BMD levels and BMI. Totally 1866 (22.3%) adolescents had low /reduced BMD, and boys had a higher rate than girls (72.6% vs 27.4%, P < .001). The rates of thinness, normal weight, overweight, and obesity were 2.8%, 57.1%, 22.3%, and 17.8%, respectively. The multivariable-adjusted (age, sex, systolic blood pressure, and height Z score) ORs (95% CIs) of low/reduced BMD associated with BMI groups (thinness, normal [reference], overweight, and obesity) were 0.59 (0.39–0.89), 1.00, 1.61 (1.41–1.84), and 1.98 (1.69–2.30), respectively (P(trend) < .001). This positive association existed in boys and girls though the differences were not significant between normal weight and thin girls. The multivariable-adjusted ORs for each 1-unit increase in BMI Z score were 1.36 (1.24–1.49) for girls, and 1.23 (1.16–1.30) for boys, and 1.26 (1.20–1.32) for all participants. We observed a positive association between BMI and low/reduced BMD in 12 to 15 years old adolescents. More attention should be paid on overweight and obese adolescents to reduce the risk of low BMD. Further studies are needed to explore the mechanisms of this association.