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Differences in body composition between Tongans and Australians: time to rethink the healthy weight ranges?
P Craig1, V Halavatau, E Comino
1Metabolism and Obesity Services, Department of Endocrinology, Royal Prince Alfred Hospital, Camperdown, NSW, Australia. p.craig@unsw.edu.au
Objective:
The prevalence of obesity varies considerably between countries when compared using the common international standard. This study investigated body size and body composition in Tongan and Australian Caucasian adults.
Design:
Cross-sectional comparative study.
Subjects:
A total of 543 Tongans and 393 Australians.
Measurements:
Weight, height, waist and hip circumference, four skinfolds, midarm circumference, elbow breadth, and body composition by bioelectrical impedance using sex- and ethnic-specific regression equations.
Results:
Tongan women (mean body mass index (BMI)+/-s.e.=32.6+/-0.4 kg/m2) were larger than Australian women (BMI=25.8+/-0.4 kg/m2), with more fat-free mass (FFM; 52.2+/-0.4; 42.6+/-0.3 kg), fat mass (37.1+/-0.7; 26.6+/-0.8 kg) and percentage body fat (%fat) (40.5+/-0.4; 37.0+/-0.5%), respectively. Tongan men also had higher BMI (Tongan= 30.3+/-0.3 kg/m2; Australian=26.5+/-0.3 kg/m2), FFM (70.2+/-0.5; 62.3+/-0.6 kg) and fat mass (23.5+/-0.6; 20.7+/-0.7 kg). When compared with Australians within the same BMI range, Tongans had significantly higher FFM, elbow width, midarm muscle area and significantly lower %fat. The %fat at BMIs of 25 and 30 kg/m2 in Australian women was equivalent to the %fat found in Tongan women at 28.8 and 35.1 kg/m2, respectively. BMIs of 25 and 30 kg/m2 in Australian men corresponded with 27.5 and 35.8 kg/m2 in Tongan men. Skinfold thicknesses, waist, hip and WHR measurements suggested differences in fat distribution and body shape between ethnic groups, particularly in women.
Conclusion:
These results suggest that the standard healthy weight ranges recommended for international use may not be appropriate standards for use in the Tongan population.