Hunger is a warning signal of the body. It is a sensation triggered by the brain, perceived as unpleasant, that causes the person concerned to ingest food.
The sensation is controlled by neurotransmitters in the hypothalamus (midbrain). This is the main control system of the central nervous system responsible for the overall function and maintenance of the internal organism.
The feelings of hunger and satiety are controlled by complex interactions in the body that are not all sufficiently researched to this day. An insufficient filling of the stomach is indicated with stomach growling, but does not trigger the known feeling of hunger. The markers for this are sometimes the amounts of glucose and insulin contained in the blood.
If the human being does not sufficiently supply the body with nutrients, this will have fatal consequences in the long term, which in extreme cases may result in starvation. This is no longer to be feared in the industrialized countries, whereas people in poor countries of the world can still be threatened by famine.
The knowledge of food intake as a hunger-destroying measure is anchored in the body of the living beings. Animals also have the instinct to go hunting on a regular basis to prevent starvation. Some animals provide supplies for hard times or winter, so they do not have to go hungry during these periods.
Not only hunger makes people eat. Thus, socialization and society have raised food to a stimulant that pursues other purposes than ensuring survival. Therefore, the appetite as a mental phenomenon is to be distinguished from hunger.
The function of the feeling of hunger is to ensure the adequate supply of nutrients to the body. This is accompanied by the feeling of satiety, which occurs when hunger is quenched and the human displays the adequate intake of nutrients.
Without the feeling of hunger, there would be a danger of not supplying the body with enough. This draws the energy needed to fulfill the daily tasks from the food. If the hunger is not satisfied for a long time, it comes to physical complaints that vary in severity and increase rapidly depending on the duration, because the body then consumes of the body's energy reserves.
How long satiety lasts varies from person to person and depends on several factors. These include on the one hand the physical condition, on the other hand, but also the activity. The more active a person is, the more energy he uses and needs. Therefore, active people have a higher calorie requirement that needs to be met through food.
In addition to the normal feeling of hunger is the cravings, which is characterized by an excessive urge for immediate food intake. However, this is a process that can be described as appetite rather than actual hunger. Physicians distinguish between physical and mental cravings.
There is also a hybrid of both. The former include, for example, hormonal cravings or those caused by hypoglycemia. Mental triggers, on the other hand, can be, for example, emotional stress or various eating disorders.
If the feeling of hunger persists for a long time without being satisfied, the brain releases hormones that cause stress. However, when hungry, the body can also release mood-enhancing hormones, which can lead to high levels of intoxication. Here is a risk of contracting various eating disorders such as anorexia or bulimia.
Permanently reduced food intake leads to depression, aggression and mood swings. In addition to the physical damage and loss of body weight, the decline in pleasure and sleep disorders are not uncommon. In the long term, the satiety feeling is disturbed. This can lead to food cravings.
Diseases associated with hunger and eating disorders include anorexia nervosa, bulimia nervosa, and binge eating. In addition, a permanent lack of food leads to a so-called hunger metabolism. The metabolism reverses and is forced to draw the necessary energy from its own reserves. Over a longer period of time, the entire metabolism turns around.
Malnutrition can also impair physical and mental development, especially at a young age. Depending on the extent of malnutrition causes massive organ damage and can ultimately end in starvation.