BMI inaccurately reflects total body and abdominal fat in Tongans

Abstract

It has been noted since the earliest European contact that Polynesian body shape and size differ from those of Europeans. The muscular build of Polynesians, such as Tongans, raises questions as to the accuracy of simple anthropometric indicators, validated for use in European populations, in Polynesians. Body mass index (BMI), total body fat and an abdominal fat window were measured in a sample of Tongan [28 male (M), 28 female (F)] and Australian Caucasian adults (39 M, 46 F), with standard anthropometric and densitometric methods. Tongan males (BMI, 32.8+/-4.6 kg/m(2)) were heavier than Australian males (BMI, 27.1+/-3.7 kg/m(2)); but differences in total body percent fat (28.9+/-8.3 vs. 25.9+/-8.1, p=0.15), abdominal fat (1.84+/-0.69 vs. 1.55+/-0.60 kg, p=0.07) and abdominal percent fat (30.3+/-8.6 vs. 28.5+/-8.3, p=0.40) were non-significant. Tongan females (BMI, 34.3+/-5.5 kg/m(2)) were also heavier than their Australian counterparts (BMI, 26.2+/-6.3 kg/m(2)); with the difference in total body percent fat (41.9+/-5.2 vs. 38.7+/-8.9, p=0.05) and abdominal percent fat (39.3+/-4.8 vs. 33.6+/-8.9, p=0.001) less than expected, given the difference in BMI. This study demonstrates significant body composition variations between Tongans and Caucasians.

Paradoxically Low Levels of Total and HMW Adiponectin in Relation to Metabolic Parameters in a Tongan Population

“…Also, there were no significant differences in HOMA and cholesterol between males and females between Tongans and controls. These population data reflect previous studies [8, 13] which noted that Tongan males (reported BMI, 32.8 ± 4.6) were only “fatter” than Australian males by BMI estimation (BMI, 27.1 ± 3.7), while any differences in total body percent fat (28.9 ± 8.3 versus 25.9 ± 8.1), abdominal fat (1.84 ± 0.69 versus 1.55 ± 0.60 kg,) and abdominal percent fat (30.3 ± 8.6 versus 28.5 ± 8.3) were nonsignificant. These studies also showed that Tongan females (reported BMI, 34.3 ± 5.5) were also “fatter” by BMI than their Australian counterparts (BMI, 26.2 ± 6.3) although the extent of the difference in total body percent fat (41.9 ± 5.2 versus 38.7 ± 8.9, P = 0.05) and abdominal percent fat (39.3 ± 4.8 versus 33.6 ± 8.9, P = 0.001) did not reflect the larger differences in BMI.…”

“…In conclusion, the Tongan population has been reported to have a novel body composition with high lean mass in comparison to the control Caucasian group [8]. This fact may influence the low total and HMW adiponectin levels we noted.…”

“…However, while Tongan men have higher weight than their Australian Caucasian counterparts, they do not have significantly more total or abdominal fat. This is largely due to a higher lean mass in Tongan men, with a similar observation made in Tongan women [8]. Such differences in body fat could affect the relationship between adiponectin and obesity/insulin resistance in the Tongan population.…”

“…These studies also showed that Tongan females (reported BMI, 34.3 ± 5.5) were also “fatter” by BMI than their Australian counterparts (BMI, 26.2 ± 6.3) although the extent of the difference in total body percent fat (41.9 ± 5.2 versus 38.7 ± 8.9, P = 0.05) and abdominal percent fat (39.3 ± 4.8 versus 33.6 ± 8.9, P = 0.001) did not reflect the larger differences in BMI. Notably, Caucasians had a significantly lower lean body and higher abdominal fat masses than Tongans with the same BMI [8, 13] highlighting underlying body composition differences not detectable by BMI comparisons.…”