[Systematic modelling in nutrition].

Live organisms can be considered as open complex systems in a steady state through which passes a flow of matter which undergoes a series of transformations which constitutes the nutritional process. The systemic approach and modelling procedure can be applied to nutrition as it can to other scientific areas, although examples of this particular application are few. This review describes the complexity of components in nutritional systems and presents a means of simplifying this. A section is given over to a comparative study of the main types of models (empirical vs mechanistic, static vs dynamic) which can be applied to nutrition. The other topics covered concern the modelling of the regulating systems in nutrition (homeostasis, homeorhesis), model validation and comments on application models and research.