Body composition estimation

Plethysmography and body composition estimation. In Figure 7.31, the usual configuration is shown with the current carrying electrodes CC and CC as the outer electrodes. 

In order to define the obese state ia a clinical setting, it is necessary to have a means of estimating the amount of adipose (fat) tissue relative to lean body mass. Whereas highly accurate determiaations of body composition require complex laboratory procedures, large clinical studies typically employ measures of skia-fold thickness (11) or more commonly, body mass iadex (BMl) as a quantitative measure of obesity. 

A number of procedures used to determine protein quality involve bioassays. Bioassays require feeding live animals protein ingredients for a specified period of time, and then estimating the nutritive value of the protein. Two such assays are the rat-based protein efficiency ratio (PER) bioassay and the human nitrogen balance assay (Dimes et al., 1994). Animal feeding experiments require chemical analyses of both the dietary inputs and then the metabolic output of the animal (e.g., body composition analysis, fecal sample analysis, collection, and assay for urine) from which the efficiency of protein metabolism can be predicted as well as how the protein supports animal growth and cell maintenance. 

Not only is the densitometric estimation of body composition affected by life cycle changes in the composition of the FFB so, too, are other methods which are based on similar assumptions. For... 

W. H. Van Itallie, T. B. (1983) Measurement of total body electrical conductivity a new method for estimation of body composition. Am. J. Clin. Nutr. 37, 735-739. 

Better markers of nutrition status and methods for determining patient-specific nutrition requirements are needed to allow further refinement of estimates of individual nutrition needs. Functional tests and simple, noninvasive tests for body composition analysis hold promise for the future. However, until better methods of assessment become available clinically and are demonstrated to be cost-effective, the currently available battery of tests will continue to be the mainstay of nutrition assessment. 

Table 8.2 Dietary Macronutrient (% energy) and Saturated Fat (SAT) (% Energy) Estimates in Worldwide Hunter-Gatherer Societies (n = 229) with Varying PlantiAnimal Subsistence Ratios and with Varying Animal (Hunted + Rshed) Body Compositions...

Segal, K.R., Gutin, B., Presta, E., Wang, J., and Van Itallie, T.B. (1985) Estimation of Human Body Composition by Electrical Impedance Methods A Comparative Study, J. Appl. Physiol. 58.1565-1571. 

If there are differences in both body composition and total energy expenditure among subjects with TCHAD deficiency, these need to be taken into account when estimating total energy requirements (Box 23.1). 

When skin electrical protection has been broken down during an electrical accident, the volume segment resistance is the current Umiting factor (cf.. Section 9.14). A description of the body immittance data used for the estimation of body composition is found in... 

Bosy-Westphal, A., Schautz, B., Later, W., Kehayias, J.J., Gallagher, D., Midler, MJ., January 2013. What makes a BIA equation unique Validity of eight-electrode multifrequency BIA to estimate body composition in a healthy adult population. Fur. J. Clin. Nutr. 67 (Suppl. 1), S14—S21. 

To the clinician, the accurate measurement of total body water (TBW) can provide indirect information concerning whole body composition and energy balance. Desiccation measurements performed on eviscerated guinea pigs in 1945 [270] led to the almost universal acceptance of the fact that lean body mass (LBM) was of constant composition — and additionally, contained all of the body water. Thus the extracellular water associated with adipose tissue was neglected and the water content of lean body mass taken as 73.2%. The following simple formula, which was readily applied to man, provided an indirect estimate of body fat ... 

Energy retention may be estimated indirectly as ME intake minus heat production, or directly from the animal s carbon and nitrogen retention in a respiration chamber. It may also be measured using the comparative slaughter technique, where a known amount of ME is given and body composition is measured at the beginning and end of the experiment. 

There have been a number of criticisms of body composition analysis studies. Firstly, intrauterine accretion estimates have assumed that stillborn fetuses were of normal size for gestational age and, therefore, that the accretion of each specific nutrient was normal for that gestational age. Based on the argument that infants who die in utero are probably not of normal size for gestational age, the estimated fetal content of each nutrient is likely an underestimate of true fetal composition. Secondly, when estimating oral requirements for the pre-term infant, the values used for absorption and excretion of nutrients were based on metabolic studies on full-term infants (Fomon and May, 1958). These values have been extra-... 

J. M. Conway, K. H. Norris, and C. E. Bodwell, A new approach for the estimation of body composition infrared interactance. The American Journal of Clinical Nutrition, 40 1123-1130,1984. 

Bioelectrical impedance (BI) measures the opposition (impedance) of biological tissues to the flow of alternating electric current. This opposition is highly correlated both with the concentrations of electrolyte ions and water in the tissues, as well as with their structure cell sizes, density, and spacing [1]. In the field of body composition, the technique is known as Bioelectrical Impedance Analysis (BIA), and it has been used for the estimation of total body water (TBW), fat-free mass (FFM) and fat mass (FM) [2]. Impedance is measured using a tetrapolar approach as described in [3]. 

SBIA measures the resistance of upper limb, lower limb and trunk in order to calculate total FFM. It also allows the analysis of body composition of specific body segments in patients with conditions like ascites, local or regional edema, and tissue deposition or depletion [5]. SBIA has also been used for estimation of hydration during hemodialysis,... 

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