title: Variations in truncal body circumferences affect fat mass quantification with bioimpedance analysis.
abstract: OBJECTIVE
  To test the hypothesis that variations in trunk circumferences influence the accuracy of bioimpedance analysis (BIA) for assessment of percent fat mass (%FM).
  
  
  METHODS
  %FM was predicted with BIA, and compared with air-displacement plethysmography (ADP) in a small sample of 35 overweight (OW), 21 normal weight and 8 underweight 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 (Diff(BIA-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 circumferences were inversely associated with resistance (R) and reactance (P<0.01), and with Diff(BIA-ADP) (P<0.001). In women, the variability in hip circumference explained 76%, and in men, the variability in waist circumference explained 59% of Diff(BIA-ADP).
  
  
  CONCLUSIONS
  Resistance changes associated with variations in trunk circumferences decrease resistance, and therefore impair the accuracy of BIA to assess %FM.
authors: Franz-Volhard Clinical Research Center at the Experimental & Clinical Research Center, Charité University Medicine Berlin and Max Delbrueck Center for Molecular Medicine, Berlin, Germany. verena.haas@charite.de
authors: V
authors: V
authors: Haas
authors: S
authors: S
authors: Engeli
authors: T
authors: T
authors: Hofmann
authors: A
authors: A
authors: Riedl
authors: S
authors: S
authors: Haufe
authors: P
authors: P
authors: Kast
authors: S
authors: S
authors: Wiesner
authors: J
authors: J
authors: Böhnke
authors: J
authors: J
authors: Jordan
authors: M
authors: M
authors: Boschmann
mesh_terms: D000273:Adipose Tissue / Q000503:physiopathology*; D050154:Adiposity; D000328:Adult; D015982:Bias; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D017097:Electric Impedance; D005260:Female; D006615:Hip / Q000033:anatomy & histology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D050177:Overweight / Q000503:physiopathology*; D010991:Plethysmography / Q000379:methods; D012016:Reference Values; D012737:Sex Factors; D013851:Thinness; D055105:Waist Circumference; D015431:Weight Loss / Q000502:physiology*; D055815:Young Adult