Most of the people think that empty stomach creates the feeling of hunger, but this is not true. Hunger has nothing to do with an empty stomach. For example, a person who has fever may have an empty stomach, but he does not feel hungry. Similarly when a child is born, he does not feel hungry for several days.
Then why do we feel hungry? We feel hungry when the energy level of our body gets low. Deficiency of nutritive elements in the blood is the main cause of hunger. Our body and our brain need energy to walk, talk and think or to do any thing. The nutrients which provide energy are mainly fat and glucose, or sugar. We have little detectors in our brains and in other organs of our bodies that keep track of our energy supply. When the energy levels get low, these little detectors sound the alarm: Energy Alert!
The hunger center is situated in the brain under the cerebral hemispheres, behind where the optic nerves cross. This is a very important region of the central nervous system called the hypothalamus. When some of these zones are stimulated, a feeling of intense hunger is created. Other zones, having the opposite effect, tell us when our hunger has been satisfied, or if we dislike certain foods. This center receives information on our body’s needs. The information is then transmitted to other nerve centers responsible for carrying out the activities associated with feeding.
When the blood gets depleted of nutritive materials, a message is sent to our brain by our body through nerves. The deficiency of nutritive materials is caused in the blood by the consumption of energy in the routine work. A sick man remains in a state of rest and consumes small amounts of energy. He, therefore, does not feel hungry for several days. Whenever there is a deficiency of nutritive food substances in the blood, a message goes to the ‘hunger centre’ of the brain. This centre acts like a brake on the activities of the stomach and intestines. When the blood has sufficient nutritive substances, the hunger centre stops the activities of the stomach and intestines. On the contrary when there is a lack of nutrition, the intestines and stomach become active. That is why you can hear your stomach rumbling when you are hungry.
As with all other feelings, hunger is caused by external and internal stimulation. External stimulation is by sight or smell. We also eat for reasons other than energy, for food’s tastes. Another example of hunger is eating to socialize or to have fun with other people.