Evidence of changing patterns of food consumption behavior is presented. Previous attempts at explaining these changes are critically reviewed and the need for an alternate approach is identified. A model of consumer behavior in which utility from food consumption is maximized subject to outlay for foods and limits on the consumption of fat, cholesterol, sodium, and/or other food components is proposed. This model yields a system of demands that are functions of prices and outlay as well as the composition of food and limits on the consumption of these components. The structure of this model is examined and restrictions on consumer food demands are derived. The derivation of individual demands based on the proposed model is demonstrated using a specific indirect utility function. Tests of the joint hypotheses that fat or cholesterol consumption determines food demand are defined. The computation of aggregate food demand elasticities with respect to changes in prices and changes in attributes such as fat or cholesterol consumption is demonstrated. Data necessary for estimating the parameters of the model and testing hypotheses are identified. The model proposed in this study allows tests of the hypothesis that food demands are not affected by food composition as well as measurement of these effects / Ph. D.