ABSTRACT
Animals eat for taste and eat for calories. The early work on food intake focused primarily on the importance of calories. As quoted from E. Scott by Jacobs and Sharma (1969), “There is only one known true hunger. This is the appetite for food as such, and in the rat at least, it is satisfied by sufficient calories. There are, to the author’s knowledge, no data to contradict the assumption that normally rats eat for calories.” This conclusion comes from the early work showing that rats compensate for dilution of their diet by consuming more, thereby maintaining a constant caloric intake (Adolph, 1947). Rats adjust to dilution even when feeding is done intragastrically, bypassing the taste system (Epstein & Teitelbaum, 1962). On the other hand, rats readily consume saccharin solutions, which have no calories, and also sham feed for sugar and other substances (e.g., Joyner, Smith, Shindlehecker, & Pfaffman, 1985), showing that palatability and sensory factors are also major determinants of food intake.
