Ethnic differences in adiposity and body composition: the First Nations bone health study.

The purpose of this study was to compare patterns of adiposity and soft tissue composition in First Nations and white Canadian women. A population-based cross-sectional study was performed. A random age-stratified sample of 206 urban First Nations women and 177 white women was recruited. Soft tissue composition was analyzed with dual-energy X-ray absorptiometry. Analysis of covariance (ANCOVA) models were used to assess ethnicity in models that adjusted for body mass, body mass index (BMI), and socio-demographic factors. Obesity (BMI>or=30.0 kg/m2) was more common in First Nations women (48.1%) than in white women (36.2%, Fisher's exact test p=0.012). Mean trunk fat tissue mass fraction and total body fat mass fraction (as a percent of soft tissue) were greater in First Nations women than in white women (p<0.0001). Trunk lean tissue was also greater in First Nations women (p=0.027), but total body lean tissue was similar. The mean trunk adiposity index was strongly related to ethnicity (First Nations +0.5%+/-2.5% versus white -1.7%+/-2.6%, p<0.0001). Preferential fat accumulation in the trunk of First Nations women persisted after adjustment for body mass, BMI, and other socio-demographic variables (p<0.0001). First Nations women differ from white women in terms of fat and lean tissue mass and distribution. First Nations women had a preferential increase in trunk fat and this may contribute to high reported rates of diabetes, metabolic syndrome, and cardiovascular events.