pene te na et NUTRITION METABOLISM CLASSIC ... Prospective Overview (continued) recommendation is amely today in that invesugiators assess the body composition of population groups whose fat-free body composition is altered by developmental status and ethnicity. As clearly shown by Lohman.” failure to use measurements of total-body water and ¥V.w.U. LIDTAK Y bone mineral content in conjunction with densitometric determinations results in an overestimation of bods fatness in children. Studies in elderly people’ and ditferent ethnic groups! also indicate the need for use of measurements of bone mineral and water to vield meaningful estimates of bodv composition. The general model used bySiri? fat = adensitv)! + b, is consistent with the equauons published by other investigators Who sought to use density to index body fatness.'* Although this model is generally acceptable. Siri acknowledged that its major limitation is sample specificitv’: itdoes not account for variations in hydration, obesity, or bone mineral density seen among individuals in the population. Furthermore. the validity of the general model has never been evaluated with direct chemical methods. The recent findings of Muscaritoli et al.'* indicate the bias in the prediction of bodyfatness with the general Siri model based only on densitometric measurements and suggest the need fora modification of the model. For more than 50 vears. densitometry has been used us a reference method for the assessment of human body composition. Siri calculated the uncertaintyof estimating bodyfatness from whole-body densitometry based on the variability of the chemical composition ofthe fat-free body. The importance of these calculations was, and continuesto be. the acknowledgmentof the need to use determinations of total-body water and bone mineral, together with body density measurements. to reduce error in the estimation of an individual's body futness 5 42098 492 NUTRITION VOL. 9 NO 4. SEPTEMBER OCTOBER 1993 because of variation in the chemical composition of the fat-free body and varying amounts of adipose ussue The significance of Siri's contributions on body-composiuon assessment is embodied in the current use of multiple independent measurements of components of the fat tree bodyto increase the validity of the body composition of children. elderly people. and various ethnic groups References 1 Sari WE Boddy comipositian from flit spaces ane density analysts af methods, Berkeley 2 4 CADononer Laboraton of Brophysies and Mecho Physics, 1950 Sti WE Body composition from fluid spaces and density. anathysis af metheds Ino Brozek [. Henschel AL eds. Technigites for mmedsirmiv body compusuion, Washington, OC Natenal Acadenn of Saences, National Research Counc 19) 224 Lukaski HC. Methods for the assessment of human body compeosition traditional and new Am f Clin Nutr 1987) 46:537 +. Belinke AR. Feen BG. Welham WE The specific gravity of healthy men JAMA 1942:9) 495 5. Kevs A. Brozek 1 Body fatin adult man. Phystal Rew 1954.43 245 6 Pace N Rathbun EN. Studies on body composition. HE The bods water ind chemically combined nitrogen in relation to fat content, J Biol Chem 1945:158:0385 7 Pitts GC Body fat accumulation 1 the guinea pig. Am J] Physiol 1950 185.41 8. Behnke AR, Osserman EF. Welham WC. Lean body muss Anh Intern Med 19S3.01.585 9 Lohman TG Advances in body composition dssesspient Champaign, TL. Human Kinetics, 1992 10 Chumleu WC. Baumgartner RN. Status of anthropometry and body composition data in elderly subjects. Am J Clin Nutr 1980.50; 1158 Wang |. Russell M) Mazanegos Mo et al Body fat by dual photon absorptiomeiry comparsons with traditional methods in Astins, Blacks and Whites Am 7 Hum Biol 192.4 401 120 Muscuntoli Wo Gieason TR. Meguid Mo etal Densitometry -hased equations for estimauny body composiion in Fischer fats, Nutrition TL LUA G 4A