Body composition analysis by leg-to-leg bioelectrical impedance and dual-energy X-ray absorptiometry in non-obese and obese individuals.
OBJECTIVE
The aim of this study is to compare total weight, % body fat (% BF), fat mass (FM) and fat-free mass (FFM) measured by bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DXA).


METHODS
This cross-sectional study included 159 women (mean age: 49.1 +/- 10.0 years) and 124 men (mean age: 51.4 +/- 8.0 years) subdivided according to sex and body mass index (BMI): BMI < 30 kg/m(2) (66 women and 50 men); BMI 30-35 kg/m(2) (53 women and 44 men) and BMI > or = 35 kg/m(2) (40 women and 30 men). Bioelectrical impedance was performed in the fasting state on a Tanita TBF-215 leg-to-leg analyser (Tanita, Tokyo, Japan). Whole-body DXA scans were performed on a Hologic QDR 4500 A bone densitometer (Hologic, Bedford, MA, USA). Total weight, % BF, FM and FFM were tested for intermethod differences. Linear regression and correlation analysis was performed. Limits of agreement and Bland-Altman plots were built.


RESULTS
DXA-derived body composition parameters were not significantly different from BIA estimates and were highly correlated (e.g. for FFM, r = 0.82-0.95). In lean individuals, BIA tended to produce lower values for FM and % BF and higher ones for FFM in comparison with DXA. This trend was reversed at BMI > 35 kg/m(2). The correlations decreased with increasing BMI. The limits of agreement were much better in men than in women and increased with increasing BMI in both sexes.


CONCLUSIONS
Compared with DXA, the leg-to-leg Tanita TBF-215 analyser accurately assessed body composition in a heterogeneous group of both sexes. In the very obese women (BMI > 35 kg/m(2)), BIA measurements should be viewed with caution.
Boneva-Asiova
Z
Z
Endocrinology Unit, Central Police Hospital, Sofia, Bulgaria.
Boyanov
M A
MA
D015502:Absorptiometry, Photon; D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000503:physiopathology*; D009767:Obesity, Morbid / Q000503:physiopathology; D012737:Sex Factors