These experiments will examine why some foods stimulate overeating (hyperphagia). This research is based on the finding that the addition of an artificial sweetener (saccharin) to high- moisture foods stimulates long-term energy intake of laboratory rats. Pre-exposing rats to either the unflavored food or saccharin in water blocks the ability of saccharin to increase energy intake; this is called the pre-exposure effect. In all experiments, rats will either be pre-exposed or not pre- exposed to flavors and then fed test diets for several weeks. Test diets will contain either no added flavor, saccharin, monosodium glutamate, citric acid, or vanilla. Experiments involving saccharin will determine whether or not rats learn relationships between the flavor of saccharin and subsequent absorption of food energy, whether or not experience with saccharin in food influences subsequent preference for saccharin, and whether or not the pre-exposure effect persists over time. The information obtained from these experiments should improve our understanding of how chemosensory stimuli influence energy intake and growth. This, in turn, will be useful for developing treatments that increase or decrease energy intake by humans and domestic animals, as well as assist those developing improved foods and beverages.
