Resumo

VELAZQUEZ-ALVA, Maria del Consuelo; IRIGOYEN-CAMACHO, Maria Esther; HUERTA-HUERTA, Raquel  e  DELGADILLO-VELAZQUEZ, Jaime. A comparison of dual energy X- ray absorptiometry and two bioelectrical impedance analyzers to measure body fat percentage and fat-free mass index in a group of Mexican young women. Nutr. Hosp. [online]. 2014, vol.29, n.5, pp.1038-1046. ISSN 1699-5198.  https://dx.doi.org/10.3305/nh.2014.29.5.7254.

Introduction: Studies of obesity require the estimation of fat mass (FM) and fat-free mass (FFM); therefore it is important to validate methods that evaluate these measurements. Objective: We sought to compare two different bioelectrical impedance analysis systems (BIAs) to estimate FM and FFM using dual-energy X-ray absorptiometry (DXA) as reference. Methods: We used a cross-sectional design. We evaluated FM and FFM using DXA and two types of BIA equipment: a foot-foot system (FFS) and a hand-footsystem (HFS). We conducted paired analysis (paired t-test). We used Bland-Altman plots to assess the relationships between FM and FFMI, limits of agreement were constructed (CL). Results: A total of 175 female students (22.9 ± 2.2 years-old) participated in the study. The paired analysis showed significant differences between the mean value of body fat percentage (BF%) estimated by BIA equipment compared to DXA (FFS = 28.7%, HFS= 34.4% and DXA= 35.3%). The mean difference between the HFS and DXA of BF% was -0.96, ((CL -5.29, 7.20). For the FFS, the mean difference was -6.69, (CL -0.29, -13.09). The paired analysis revealed significant differences between the estimates of FFMI by BIA compared to DXA (FFS =16.29, HFS =14.95, DXA =14.18). The mean difference between HFS and DXA was 0.78, and (CL -2.27, 0.72) whereas the FFS mean difference was -2.11 (CL -3.73 -0.49). Conclusion: A different magnitude of bias was observed between the BIA equipment arrays. The HFS appears to be more reliable than the FFS used, particularly in obtaining FFMI in young women.

Palavras-chave : Body composition; Body fat; Fat-free mass index; BIA; DXA; Validation.

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