Background aims: Body composition measurements seem to be not reliable enough in obese patients. Our aim was to compare single frequency-bioelectrical impedance (SF-BIA) analysis; foot-to-foot impedance meters (FFI) or upper body fat analysers (UBFA) and DXA (Dual-energy X-ray absorptiometry) in severely obese patients.
Patients and methods: Cross-sectional study including 40 severely obese patients. Bioelectrical impedance was performed for SF-BIA (Holtain (H) and OMRON BF 500 (O500)), FFI (Tanita TBF-300 (T)) and UBFA (Omron BF 300 (O300)). DXA scans were performed using a Lunar iDXA. The data were analysed using Pearson's correlation and Bland Altman plots were also drawn to evaluate any agreements.
Results: The percentage and total body fat values were 49.2% and 55.2 kg measured with DXA, 44.3%/53.4 kg with O300, 50.6%/58.3 kg with O500, 45.4%/55.4 kg with H and 49.1%/60.3 kg with T. The Holtain BIA showed the worst correlation with DXA for both %BF and FFM. Although the measurements of % body fat, fat mass and fat-free mass were significantly correlated with DXA, each method showed wide limits of agreement, although T was most closely correlated with DXA.
Conclusion: Compared to DXA, FFI and UBFA could be useful for assessing body composition in severely obese people, although they appeared to underestimate %BF and FM and their limits of agreement were too wide.