Interpretation of nutrient-response relationships in rats

Nutrient-response curves are nonlinear and, as is true of other curves that define the rates of biological reactions, these curves can be described by rational polynomials. These nutrient-response curves presumably reflect the metabolic fate of the nutrient. Data reported for the accumulation of body nitrogen in rats fed three different proteins are interpreted in terms of the biochemical systems theory and metabolic control theories. Analysis of the rational polynomials that define the nutrient-response curves permits partitioning the nutrient between a number of grossly defined metabolic pathways. The power law formalism of the biochemical systems theory is discussed with respect to the well-established relationship between body weight and basal energy requirement.