Estimating body fat from anthropometry and isotopic dilution: a four-country comparison.
OBJECTIVE
The goal was to assess the ability of BMI to predict body fat (BF) among youths in four countries and identify the degree to which additional anthropometric measures improve this prediction. BMI is widely recommended as an indicator of overweight. However, whether BMI adequately estimates BF and has the same meaning in different ethnic groups and youths has been questioned.


METHODS
Data come from 456 Filipino, Chinese, Russian, and black South African youths, 6 to 16 years old. Percentage BF and fat mass index (FMI) were estimated by the deuterium dilution method. Skinfold thicknesses (triceps, subscapular, and suprailiac) and weight and height measures were collected. Percentage BF was regressed first on BMI and age and then with the addition of the skinfold measures. Linear models were run separately by country and sex. The models were repeated with FMI as the outcome.


RESULTS
The R2 values from the percentage BF models ranged from 0.13 to 0.69 in the first models to 0.38 to 0.81 in the full models. The values were lowest among Russian males > or = 13 years and Russian females > or = 13 years of age in the reduced and full models, respectively, and were highest among Chinese females. Using FMI as the outcome did not meaningfully change the results.


CONCLUSIONS
The ability of BMI to adequately predict BF and the additional predictivity of anthropometric measures varied widely across the samples, making its uniform use as a proxy for BF in youths from different countries questionable.
Eckhardt
Cara L
CL
Department of Nutrition and Carolina Population Center, University of North Carolina, Chapel Hill, North Carolina 27516-2524, USA. cara_eckhardt@unc.edu
Adair
Linda S
LS
Caballero
Benjamin
B
Avila
Josephine
J
Kon
Igor Y
IY
Wang
Jinzhong
J
Popkin
Barry M
BM
D000273:Adipose Tissue / Q000502:physiology*; D000293:Adolescent; D000886:Anthropometry / Q000379:methods; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D002648:Child; D002681:China; D017666:Deuterium Oxide / Q000737:chemistry; D005260:Female; D006801:Humans; D007201:Indicator Dilution Techniques; D016014:Linear Models; D008297:Male; D009031:Moscow; D010679:Philippines; D012044:Regression Analysis; D012463:Saliva / Q000737:chemistry; D012885:Skinfold Thickness; D013019:South Africa
D017666:Deuterium Oxide