Title of article:

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

Authors: He M, Tan KC, Li ET, Kung AW.
Journal: Int J Obes Relat Metab Disord, May 2001;25(5):748-52

Abstract

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-Pacific Region recommended jointly by the International Association for the Study of Obesity, the International Obesity Task Force and the WHO are appropriate 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 content (%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 the formula significantly under-predicted %BF by 1.1% in males and 3.4% in females. A predicted BMI of 25 and 30 kg/m(2) using a Caucasian-based formula corresponds to an actual BMI of 23 and 25 kg/m(2), respectively. On linear regression analysis, 25% BF corresponds to a BMI of 24.6 kg/m(2) 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 occur at a lower BMI. Our results would support the recommendations of using lower BMI cut-offs to define obesity in the Asia Region.

Comments and Key points

It's nice to read a consice article like this, that presents its data with completeness, and makes decent interpretation and conclusions.

The article says that "In Asians, the new proposed cut-offs for overweight and for obesity are >=23.0 and >=25.0 kg/m2."

Here's some of their data. I'm particularly interested to point out the relatively high body fat percentages in Hong Kong women, with relatively low BMI values.

  20-30yrs 31-40 41-50 51-60 >60 all
Males            
median BMI 21.5 23.7 23.8 21.7 23.7 23.0
% body fat 18.0% 23.9% 23.5% 22.1% 26.9% 23.0%
             
Females            
median BMI 20.3 21.3 23.2 23.2 243.2 22.4
% body fat 29.7% 32.6% 36.6% 38.5% 39.3% 35.2%

- "In men, a 25% body fat percentage correspondes to a mean BMI of 24.6. In women, a 35% body fat percentage corresponds to a mean BMI of 22.6."

Ah ha. It appears they are already using 25% (men) and 35% (women) body fat percentage as a definition of obesity. That's higher (in women) than the often seen 30% criteria, and higher than the 33% that is also reasonably common. Where did they get their 35% criteria? From Deurenberg1.

 

References

  1. Deurenberg P, Yap M, van Staveren WA. Body mass index and percent body fat: a meta analysis among different ethnic groups. Int J Obes Relat Metab Disord 1998; 22:1164-1171.

Review & comments by Steven B. Halls, MD, Lasted edited 23-June, 2008, Copyright.
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