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Bioelectrical Impedance Underestimates Total and Truncal Fatness in Abdominally Obese Women
Author(s) -
Neovius Martin,
Hemmingsson Erik,
Freyschuss Bo,
Uddén Joanna
Publication year - 2006
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1038/oby.2006.199
Subject(s) - bioelectrical impedance analysis , medicine , waist , overweight , anthropometry , obesity , body mass index , confidence interval , body fat percentage , circumference , obstetrics , mathematics , geometry
Objective: To compare estimates of total and truncal fatness from eight‐electrode bioelectrical impedance analysis equipment (BIA 8 ) with those from DXA in centrally obese women. The secondary aim was to examine BMI and waist circumference (WC) as proxy measures for percentage total body fat (%TBF) and truncal body fat percentage (tr%BF). Research Methods and Procedures: This was a cross‐sectional study of 136 women (age, 48.1 ± 7.7 years; BMI, 30.4 ± 2.9 kg/m 2 ; %TBF DXA , 46.0 ± 3.7%; WC, 104 ± 8 cm). Fatness was measured by DXA and Tanita BC‐418 equipment (Tanita Corp., Tokyo, Japan). Agreement among methods was assessed by Bland‐Altman plots, and regression analysis was used to evaluate anthropometric measures as proxies for total and abdominal fatness. Results: The percentage of overweight subjects was 41.9%, whereas 55.9% of the subjects were obese, as defined by BMI, and all subjects had a WC exceeding the World Health Organization cut‐off point for abdominal obesity. Compared with DXA, the BIA 8 equipment significantly underestimated total %BF (−5.0; −3.6 to −8.5 [mean; 95% confidence interval]), fat mass (−3.6; −3.9 to −3.2), and tr%BF (−8.5; −9.1 to −7.9). The discrepancies between the methods increased with increasing adiposity for both %TBF and tr%BF (both p < 0.001). Variation in BMI explained 28% of the variation in %TBF DXA and 51% of %TBF BIA8 . Using WC as a proxy for truncal adiposity, it explained only 18% of tr%BF DXA variance and 27% of tr%BF BIA8 variance. The corresponding figures for truncal fat mass were 49% and 35%, respectively. No significant age effects were observed in any of the regressions. Discussion: BIA 8 underestimated both total and truncal fatness, compared with DXA, with higher dispersion for tr%BF than %TBF. The discrepancies increased with degree of adiposity, suggesting that the accuracy of BIA is negatively affected by obesity.