Bone mineral density and adipose tissue distribution in young women: relationship to smoking status

Interrelationships between anthropometric variables and bone mineral density (BMD) may allow simple and inexpensive identification of those at risk for low bone density and osteoporosis. Risk appraisal is particularly important in young women, as lifestyle modifications may slow the rate of bone loss through adulthood and decrease the risk of osteoporosis later in life. Though weight, height and body mass index are frequently assessed in relation to bone, adipose tissue distribution has rarely been considered. Smoking is associated with low bone density and abdominally localized adipose tissue. The relationship between smoking, adipose tissue distribution and BMD in women has not been examined. Regional and whole-body BMD were assessed by dual-energy X-ray absorptiometry, and adipose tissue distribution using the anthropometric indicator, waist-to-hip girth ratio (WHR), in 52 women (25 smokers, and 27 nonsmokers) aged 20-35 years. There were significant (p < 0.05) positive correlations between WHR and BMD for smokers and nonsmokers separately (r = 0.44-0.57), and for the sample overall (r = 0.30-0.51). Most relationships remained significant after adjustment for weight. Smokers did not differ significantly from nonsmokers in relationships between WHR and BMD. The results indicate a positive relationship between BMD and abdominal relative to gluteal-femoral adiposity. This relationship is independent of smoking status. The biological determinants underlying a relationship between BMD and WHR require consideration before inferences regarding BMD can reasonably be considered on the basis of WHR.