Variations in truncal body circumferences affect fat mass quantification with bioimpedance analysis
Résumé
Objective: To test the hypothesis that variations in trunk circumferences influence the accuracy of bioimpedance analysis (BIA) for assessment of percent fat mass (%FM). Subjects and methods: %FM was predicted with BIA and compared with air-displacement plethysmography (ADP) in a small sample of 35 overweight (OW), 21 normal weight (NW), and 8 underweight (UW) volunteers. Waist and hip circumferences were assessed, and 15 of the OW subjects were measured before and after weight reduction. Results: BIA and ADP provided similar cross-sectional estimates of group mean %FM (28.9 ± 10.0 and 31.3 ± 13.0%, respectively). However within individuals, there were large between-method differences (DiffBIA-ADP) ranging from -13 to +13 %FM. Furthermore, we found a systematic bias of BIA related to the degree of adiposity. Consequently, %FM and fat mass loss during weight reduction in OW were underestimated with BIA when compared with ADP. Waist and hip circumference were inversely associated with resistance and reactance (p < 0.01), and with DiffBIA-ADP (p < 0.001). In women, the variability in hip circumference explained 76%, and in men variability in waist circumference explained 59% of DiffBIA-ADP. Conclusion: Resistance changes associated with variations in trunk circumferences decrease resistance and therefore impair the accuracy of BIA to assess %FM.
Domaines
Alimentation et Nutrition
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