Hunger is not always associated with conscious internal sensation, and we sometimes find ourselves eating without having had any previous awareness of hunger pangs. Many times external cues are used to signal initiation of eating behavior. When asked if they are hungry, many people consult their watches rather than their stomachs. When someone he or she is hungry, the sensation most often reported is the feeling of slight ache in the stomach. In a famous study by Cannon (1912), a subject swallowed a balloon which allowed the experimenters to record stomach contractions and compare to the subject feeling of hunger. Cannon found a strong association between stomach contraction and feeling of hunger. Later studies have not verified this research.

             Several other theories that attempt to explain eating behavior involve body temperature, glucose level, and body fat. Glucostatic theory of hunger, first proposed by Jean Mayer (1953) argued that hunger occurs when glucose metabolism in individual cells is low.

(Hypothalamus)

                 Psychologists and physiologists have long sought to find other conditions in the body that trigger hunger. For instance, it has been suggested that a high rate of use of blood sugar, or glucose, such as might occur after fasting, is cause of a hunger. Another recent idea is that changes in the metabolic functions of the liver when the fuel supplies are low provide the bodily stimulus for hunger (Friedman and Striker, 1976). It has been proposed that the liver can in some way signal a part of the brain known as the hypothalamus that more fuel is needed, thus triggering hunger motivation.