Use of universal BMI and waist cut-points is inappropriate for comparing obesity prevalence among differing ethnic groups

A total of 721 healthy women aged 18-60 years from South Africa (SA) and New Zealand (NZ) were studied to investigate body composition differences among five ethnic groups (white Caucasians, sub-Saharan Africans, Maori, non-Maori Pacific Islanders and Asian Indians). Measurements included anthropometry, body fat, bone mineral content and total appendicular skeletal muscle mass (ASMM) by X-ray absorptiometry. For a BMI of 30 kg/m2, SA European women had a % body fat of 39%, which corresponded to a BMI of 29 for SA black women. For a BMI of 30 kg/m2 in NZ Europeans, equivalent to 43% body fat, the corresponding BMIs for NZ Maori, Pacific and Asian Indians were 34, 36 and 26 kg/m2, respectively. In SA, central fat mass was lower in black than in European women (P<0.001). In NZ, central fat mass was the lowest in Pacific women and the highest in Asian Indians whereas ASMM was the highest in Pacific women and the lowest in Asian Indians. Therefore, the relationship between % body fat and BMI varies with ethnicity, which may be due to differences in central fatness and muscularity. Use of universal BMI or waist cut-points may not be appropriate in this respect, as they do not provide a consistent reflection of adiposity and fat distribution across ethnic groups.

Abstract