Body composition techniques
Body composition techniques can be
described in terms of direct, indirect, and doubly indirect methods.
● In direct methods, the body component of interest is determined
directly without or with only minor assumptions. Examples are chemical carcass
analy-ses and IVNAA for the atomic components.
● In indirect techniques, the body component of interest is determined indirectly. Examples are the determination of body protein from body nitrogen, assuming a constant conversion factor of 6.25 from nitrogen to protein, and the determination of body cell mass using 40K. In both examples, assumptions are used. These assumptions may not be valid in the given situation or for the subject(s) under study and hence could lead to biased results.
● Doubly indirect methods rely on a statistical rela-tionship
between easily measurable body para-meter(s) and the body component of
interest. Examples are the assessment of skeletal muscle mass by creatinine
excretion and the assessment of body fat from skin-fold thickness. Table 2.4
gives an over-view of the most common methods.