Abstract
During the past 10 yr, renewed interest has been expressed in the mechanisms controlling the intake of specific dietary components. In particular, this interest has focused on research examining the role of the central nervous system in regulating intake of the three macronutrients protein, fat, and carbohydrate. Several hypotheses relating specific neurotransmitter systems to nutrient selection have developed from this research. However, conflicting data make the acceptance of any one hypothesis about diet selection untenable. As an attempt to reconcile some of the conflicting data, the present paper describes a variety of factors which can influence patterns of nutrient choice. The effects of diet composition, the experimental environment, the animals' background, and nutritional history on diet selection are examined.