Modeling in nutrition and metabolism.

Fundamentals of modeling of in vivo nutritional and metabolic systems are discussed. Emphasis is placed upon the potential usefulness of models, and the relationship between utility and model complexity. With the glucose regulating system used as a metaphoric example, the balance between available data and model simplification is drawn, with the goal of obtaining a representation of optimal complexity. From such an optimization procedure, it is argued that the maximum usefulness of models can be obtained with respect to the testing of specific physiological hypotheses, and the estimation of unmeasurable parameters or variables. The view is expressed that only with careful modeling procedures, in which principles of optimal complexity are applied, will the impact of models of nutritional systems be significant.