Have you noticed how some people feel hungry all the time while some of us do not feel hungry till quite some time? It is a common belief that an empty stomach leads to hunger. But this is not true. Of course, one begins to experience a feeling of hunger when the stomach is practically empty but hunger is more associated with the nutritive materials in the blood. When the blood runs short of nutritive materials, a message is sent to our brain by our body through the nerves. How does the blood run short of nutrition? As we continue to do our daily routine work, the body consumes energy. Slowly, the nutritive element in our blood reduces till it runs short of the requirement. A sick man rests most of the time and hardly consumes any energy. He, therefore, does not feel hungry for several days. Whenever the hunger centre of the brain receives a message about the lack of nutritive materials in the blood, it acts like a brake on the activities of the stomach and intestines. When the blood gets sufficient nutritive substances, the hunger centre stops the activities of the stomach and intestines. On the other hand 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. The stomach is usually conditioned or trained to ‘expect‘ food at certain fixed times every day. In such times, peristalsis begins and gastric juices are released. They produce hunger pangs and, at times, a ‘growling‘ stomach. When we feel hungry, we do not demand any particular kind of food. A starved person will eat any kind of food. The main constituents of food are — proteins, carbohydrates, fats, minerals, vitamins and water. Each component has a specific role to play. Proteins are nitrogenous compounds that are used for the growth of the body, and for the repair of muscles and tissues. Carbohydrates and fats produce heat energy in the body. Minerals build the bones and tissues. Vitamins help to protect the body from some diseases. Water is the main constituent of the cells. It carries the nutritive substances and oxygen to different parts of the body. The deficiency of any nutritive substances results in illness. Hence, it is deficiency of nutritive elements in the blood and not an empty stomach that causes hunger.