Body fat determination by dual energy X-ray absorptiometry and its relation to body mass index and waist circumference in Hong Kong Chinese

OBJECTIVE: To determine the relationship between percent body fat and body mass index (BMI) in the Chinese population of Hong Kong and to investigate whether the newly proposed lower BMI cut-offs for obesity in the Asia-Pacif ic Region recommended jointly by the International Association for the Stud y of Obesity, the International Obesity Task Force and the WHO are appropri ate for Hong Kong Chinese. METHODS: A total of 190 female and 140 male healthy subjects were recruited from the community. BMI was calculated as weight/height(2). Body fat conte nt (%BF) was measured by dual-energy X-ray absorptiometry (DEXA). RESULTS: Comparing %BF measured by DEXA with predicted %BF derived from BMI using a prediction formula developed in Caucasian population showed that t he formula significantly under-predicted %BF by 1.1% in males and 3.4% in f emales. A predicted BMI of 25 and 30 kg/m(2) using a Caucasian-based formul a corresponds to an actual BMI of 23 and 25 kg/m2, respectively. On linear regression analysis, 25% BF corresponds to a BMI of 24.6 kg/m2 in males and a waist circumference of 86 cm; 35% BF corresponds to a BMI of 22.6 kg/m(2 ) and a waist circumference of 73.5 cm in females. CONCLUSION: Hong Kong Chinese population have a higher %BF for a given BMI which would partly explain why the health risks associated with obesity occ ur at a lower BMI. Our results would support the recommendations of using l ower BMI cut-offs to define obesity in the Asia Region.