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This Article Full Text Full Text (PDF) All Versions of this Article: 287/5/E962    most recent 00104.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Silva, A. M. Articles by Heshka, S. Search for Related Content PubMed PubMed Citation Articles by Silva, A. M. Articles by Heshka, S.

Three-compartment model: critical evaluation based on neutron activation analysis

¹Exercise and Health Laboratory, Faculty of Human Movement-Technical University of Lisbon, 1495-688 Lisbon, Portugal; ²New York Obesity Research Center, St. Luke's-Roosevelt Hospital, Columbia University Institute of Human Nutrition, College of Physicians and Surgeons, New York City 10025; ³Department of Medicine, Winthrop-University Hospital, Mineola, New York 11501; and ⁴John Hancock Center for Physical Activity and Nutrition, Friedman School of Nutrition Science and Policy at Tufts University, Boston, Massachusetts 02111

Submitted 1 June 2004 ; accepted in final form 1 June 2004

There is renewed interest in Siri's classic three-compartment (3C) body composition model, requiring body volume (BV) and total body water (TBW) estimates, because dual-energy X-ray absorptiometry (DEXA) and in vivo neutron activation (IVNA) systems cannot accommodate subjects with severe obesity. However, the 3C model assumption of a constant ratio () of mineral (M) to total body protein (TBPro) and related residual mass density (D_RES) based on cadaver analyses might not be valid across groups differing in sex, race, age, and weight. The aim of this study was to derive new 3C model coefficients in vivo and to compare these estimates to those derived by Siri. Healthy adults (n = 323) were evaluated with IVNA and DEXA and the measured components used to derive and D_RES. For all subjects combined, values of and D_RES (means ± SD, 0.351 ± 0.043; 1.565 ± 0.023 kg/l) were similar to Siri's proposed values of 0.35 and 1.565 kg/l, respectively. However, and D_RES varied significantly as a function of sex, race, weight, and age. Expected errors in percent body fat arising by application of Siri's model were illustrated in a second group of 264 adults, including some whose size exceeded DEXA limits but whose BV and TBW had been measured by hydrodensitometry and ²H₂O dilution, respectively. Extrapolation of predictions by newly developed models to very high weights allows percent fat error estimation when Siri's model is applied in morbidly obese subjects. The present study results provide a critical evaluation of potential errors in the classic 3C model and present new formulas for use in selected populations.

body composition models; obesity; total body water; underwater weighing