Introduction to modeling.

A model is a representation of structure and a mathematical model describes mathematically the relationship between variables and/or parameters. Numerous types of mathematical models have been used to study biological systems that are of interest to nutritionists. This paper introduces some concepts that relate to the dynamic behavior of biological systems and discusses two modeling approaches that can be used in conjunction with kinetic studies. The two approaches, empirical compartmental modeling and model-based compartmental analysis, are subcategories of compartmental analysis. The objective of this brief introduction to modeling is to encourage more nutritionists to use compartmental analysis and other forms of mathematical modeling in their research.