Prediction of percentage body fat from anthropometry and bioelectrical impedance in Singaporean and Beijing Chinese

Body composition was measured in 205 male and female Beijing Chinese and in 148 male and female Singaporean Chinese, age 34 (mean) (range 18-68) years and body mass index (BMI) 22.3 (15.9-38.5) kg/m(2). In Beijing Siri's two- compartment model based on densitometry was used as a reference technique a nd in Singapore Siri's three-compartment model based on densitometry and de uterium oxide dilution was used. In addition, body composition was predicte d using equations based on anthropometry and bioelectrical impedance develo ped in Caucasian populations. Percentage body fat (BF%) predicted from BMI was systematically underestimated by about 1% in Beijing Chinese and by abo ut 3.5% in Singaporean Chinese. The difference in bias (measured minus pred icted BF%) between the two population groups could be explained by differen ces in frame size. The Durnin and Womersley equations for BF% based on skin fold thickness predicted BF% in the male and female Chinese groups adequate ly, with only a slight (less than 1% body fat) and not significant bias. Th e prediction of BF% based on the waist circumference (Lean's formula) resul ted in an unbiased estimate of BF% in females (bias about 1% body fat), whe reas in males the formula systematically underestimated BF% by 3.5-5%. Bioe lectrical impedance underestimated BF% systematically by 3%, in males and f emales to about the same extent. The bias of all prediction formulas was po sitively correlated with the level of body fatness and, except for impedanc e, also negatively correlated with age. The negative association of the bia s with age indicates that the age-related increase in body fatness is lower in Chinese than in Caucasians. It can be concluded of the studied predicti on techniques that only the skinfold methodology using the equations of Dur nin and Womersley give valid mean estimates for both Chinese males and fema les. The other techniques require the development of population-specific pr ediction formula.