Effect of cardiometabolic risk factors on the relationship between adiposity and bone mass in girls

BACKGROUND/OBJECTIVE: Childhood obesity has been separately associated with cardiometabolic risk factors (CMR) and increased risk of fracture. However, both augmented and compromised bone mass have been reported among overweight/obese children. Metabolic dysfunction, often co-existing with obesity, may explain the discrepancy in previous studies. The aim of this study was to examine whether the relationship between adiposity and dual-energy x-ray absorptiometry (DXA) derived bone mass differed in young girls with and without CMR(s). SUBJECTS/METHODS: Whole body bone and body composition measures by DXA and measures of CMR (fasting glucose, high density lipoprotein cholesterol-HDL-C, triglyceride-TG, systolic and diastolic blood pressure, waist-circumference-WC) were obtained from 307, 9–12 year old girls. Girls with 1 or ≥ 2 CMR(s) were considered to be at risk (vs. no CMR). Multiple linear regression was used to test the relationship of total fat mass with total body bone mineral content (BMC) after controlling for height, lean mass, CMR risk, and other potential confounders. RESULTS: There was a significant interaction between CMR risk and total body fat mass. When girls were stratified by CMR group, all groups had a significant positive relationship between fat mass and BMC (p<0.05), however girls with ≥ 2 CMRs had a lower BMC for a given level of body fat. Total body fat was not significantly related to bone mineral density (p>0.05). CONCLUSION: Fat mass has a positive relationship with BMC even after controlling for lean mass. However, the positive relationship of fat mass with BMC may be attenuated if multiple CMRs are present.