Sugars and fat play a unique role in the human diet. The selective choice of sugars and fat as chief energy sources seems to be influenced less by the body's energy needs than by the sensory appeal of sweet and fat-rich foods. This appeal typically holds not only across individuals but across cultures. Although many behavioral, social, and cultural factors play major roles in diet selection, people respond primarily to the sensory qualities of food. Some clinical studies have reported that individual food choices and therefore the macronutrient composition of the diet are influenced directly by the central nervous system. However, broader population-based studies point to the central role of taste in determining food selection. Survey studies have shown that the global consumption of sugars and fat is further determined by such variables as income, socioeconomic status, and the availability of sugars and fat in the food supply. Nutrition intervention strategies aimed at promoting dietary change in communities ought therefore to consider not only physical health, but also the sensory pleasure response, and a wide range of demographic, economic, and sociocultural variables.