title: Assessment of body composition in subjects with metabolic syndrome comparing single-frequency bioelectrical impedance analysis and bioelectrical spectroscopy.
abstract: BACKGROUND
  The aim of this study was to investigate the agreement between body composition measurements made with two methods-single-frequency bioelectrical impedance analysis (SF-BIA) and bioelectrical impedance spectroscopy (BIS).
  
  
  METHODS
  The body composition measurements using SF-BIA and BIS were performed seven times during 6 months on 41 patients (13 men and 28 women) with metabolic syndrome who were taking part in a dietary intervention study.
  
  
  RESULTS
  The mean [standard deviation (SD)] fat mass (FM) and median [interquartile range (IQR)] FM% measured with SF-BIA were 32.7 (6.7) kg and 36.3 (30.3-39.3)%, respectively, compared with 38.2 (8.7) kg and 40.9 (35.5-45.6)%, respectively, using BIS. The median (IQR) fat-free mass (FFM) was 60.0 (53.3-73.5) kg according to SF-BIA and 55.4 (48.8-66.5) kg according to BIS. These results obtained with the two methods were significantly different (P<0.001). Still highly significant correlations were found between the results obtained with SF-BIA and BIS for FM and FFM (all r≥0.89, P<0.001). Using Bland-Altman analysis, the bias was found to be -5.4 (4.1) kg for FM, -5.5 (3.7)% for FM%, and 5.4 (4.1) kg for FFM. Rather wide limits of agreement were found for FM, FM%, and FFM.
  
  
  CONCLUSIONS
  Body composition data obtained using SF-BIA and BIS in subjects with metabolic syndrome were highly correlated but not interchangeable. FM was systematically lower when using SF-BIA than when using BIS.
authors.affiliation: 1 Biomedical Nutrition, Department of Pure and Applied Biochemistry, Centre for Applied Life Sciences, Lund University , Lund, Sweden .
authors.forename: Lieselotte
authors.initials: L
authors.lastname: Cloetens
authors.forename: Anna
authors.initials: A
authors.lastname: Johansson-Persson
authors.forename: Hannah
authors.initials: H
authors.lastname: Helgegren
authors.forename: Mona
authors.initials: M
authors.lastname: Landin-Olsson
authors.forename: Matti
authors.initials: M
authors.lastname: Uusitupa
authors.forename: Björn
authors.initials: B
authors.lastname: Åkesson
authors.forename: Gunilla
authors.initials: G
authors.lastname: Önning
mesh_terms: D000465:Algorithms; D001823:Body Composition; D015992:Body Mass Index; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D024821:Metabolic Syndrome / Q000175:diagnosis* / Q000178:diet therapy / Q000378:metabolism*; D008875:Middle Aged; D012727:Sex Characteristics; D013057:Spectrum Analysis; D055105:Waist Circumference