Comparison of multifrequency bioelectrical impedance analysis with dual-energy X-ray absorptiometry for assessment of percentage body fat in a large, healthy population.
BACKGROUND
Bioelectrical impedance analysis (BIA) is widely used in clinics and research to measure body composition. However, the results of BIA validation with reference methods are contradictory, and few data are available on the influence of adiposity on the measurement of body composition by BIA.


OBJECTIVE
The goal was to determine the effects of sex and adiposity on the difference in percentage body fat (%BF) predicted by BIA compared with dual-energy X-ray absorptiometry (DXA).


METHODS
A total of 591 healthy subjects were recruited in Newfoundland and Labrador. %BF was predicted by using BIA and was compared with that measured by DXA. Methods agreement was assessed by Pearson's correlation and Bland and Altman analysis. Differences in %BF among groups based on sex and adiposity were analyzed by using one-factor analysis of variance with Bonferroni correction.


RESULTS
Correlations between BIA and DXA were 0.88 for the whole population, 0.78 for men, and 0.85 for women. The mean %BF determined by BIA (32.89 +/- 8.00%) was significantly lower than that measured by DXA (34.72 +/- 8.66%). The cutoffs were sex specific. BIA overestimated %BF by 3.03% and 4.40% when %BF was <15% in men and <25% in women, respectively, and underestimated %BF by 4.32% and 2.71% when %BF was >25% in men and >33% in women, respectively.


CONCLUSIONS
BIA is a good alternative for estimating %BF when subjects are within a normal body fat range. BIA tends to overestimate %BF in lean subjects and underestimate %BF in obese subjects.
Sun
Guang
G
Discipline of Genetics, Faculty of Medicine, Memorial University of Newfoundland, St John's, Canada, and Newlab Clinical Genetics, St John's, Canada. gsun@mun.ca
French
Curtis R
CR
Martin
Glynn R
GR
Younghusband
Ban
B
Green
Roger C
RC
Xie
Ya-Gang
YG
Mathews
Maria
M
Barron
Jane R
JR
Fitzpatrick
Donald G
DG
Gulliver
Wayne
W
Zhang
Hongwei
H
D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D000328:Adult; D001823:Body Composition; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009523:Newfoundland and Labrador; D049629:Waist-Hip Ratio