Journal of the American College of Nutrition, Vol 14, Issue 6 652-655, Copyright © 1995 by American College of Nutrition

JOURNAL ARTICLE

Comparison of body composition measured by total body potassium and infrared interactance

M. A. Flynn, G. B. Nolph and G. Krause
Department of Family and Community Medicine, School of Medicine, University of Missouri-Columbia, USA.

OBJECTIVE: The purpose of this study was to find how closely a near infrared instrument (IRI), Futrex 5000, would compare to whole body counting (WBC) of potassium-40 (40K) in assessing body composition. DESIGN: We measured lean body mass (LBM) and percent total body fat (PCF) in 177 males and 27 females by total body potassium (TBK) and by infrared interactance (IRI). TBK was assessed by 2 pi whole body counter (WBC) and IRI by Futrex (F) instrument. These subjects were measured for TBK and for IRI within 1 week of each other. RESULT: A large mean difference (p < or = 0.001) was found between the results using the two instruments: IRI data for LBM were higher and PCF lower compared to TBK. CONCLUSION: As shown by repeated TBK measurements over a 22-year period in these same volunteers, this technique is reliable. The IRI assessments did not come to a close fit with TBK.