ARS | Publication request: Comparison of Fat-Free Mass and Body Fat in Swiss and American Adults

Submitted to: Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 21, 2004
Publication Date: April 30, 2005
Publisher's URL: http://www.elsevier.com/locate/nut
Citation: Kyle, U.G., Genton, L., Lukaski, H.C., Dupertuis, Y.M., Slosman, D.O., Hans, D., Pichard, C. 2005. Comparison of fat-free mass and body fat in Swiss and American adults. Nutrition 21:161-169.

Interpretive Summary: A variety of noninvasive methods for assessment of human body composition are available. One method, bioelectrical impedance analysis, is commonly used internationally. Because investigators rely on large samples of the population to validate prediction equations derived by using the impedance method, there is a controversy if prediction equations from one population are valid in another population. This study evaluated a prediction model generated from data collected in the US National Health and Nutrition Examination Survey (NHANES III) in a 7000 healthy Swiss adults. Overall, the US equation accurately predicted both lean and fat masses in the Swiss men, but overestimated lean and fat in the Swiss women. These findings support the generalized use of the impedance method but caution estimates for women. Discrepancy in estimation of body composition is attributed to the increased body weight of the US compared to the Swiss women. This information will be useful for public health professional who seek to assess the body composition of adults in population-based surveys of health.

Technical Abstract: Objective: No current studies have compared North American with European body composition parameters, i.e., fat-free mass (FFM), body fat (BF), and percentage of BF (%BF) in large populations. This study compared FFM, BF, and %BF values derived from two bioelectrical impedance analysis (BIA) equations (Geneva and National Health and Nutrition Examination Survey [NHANES]) in Swiss subjects and compared FFM, BF, and %BF values of white Swiss with those of white North American adults with the same BIA equations. Methods: Healthy adults (3714 men and 3199 women), ages 20 to 79 y, in Switzerland were measured by single-frequency BIA and compared with means and standard deviations for body mass index and body composition parameters obtained from the NHANES III study (United States; n = 2538 men, 2862 women). FFM was calculated with the Geneva and NHANES equations. Results: Mean FFN GENEVA values did not differ from FFN NHANES values in men but was significantly lower (-1.5 kg) in women. FFM and BF values in American men, who weighed 4.2 to 12.0 kg more than the Swiss men, were significantly higher (+2.1 to +6.0 kg and +1.5 to +6.4 kg respectively) than those in the Swiss men. FFM and BF values in American women, who weighed 2.3 to 12.1 kg more than the Swiss women, were significantly higher (+1.3 to +2.1 kg and +4.8 to +11.8 kg, respectively, except FFN in subjects ages 20 to 29 y and BF in those ages 70 to 79 y) than FFM GENEVA values in Swiss women. FFM in American women was significantly lower (+1.3 and +1.9 kg) and non-significantly higher than FFN NHANES in Swiss women. Conclusion: NHANES and Geneva BIA equations estimate body composition equally well in men, but further research is necessary to determine the discrepancies in FFM between BIA equations in women. The greater weight of the American subjects yielded higher values for FFM, BF, and %BF in American than in Swiss men and women.