A feeling of satiety is a bodily signal that occurs when eating and shows the person eating that he or she cannot take in any more food. It is controlled by the brain and is a complex process, the details of which have not yet been fully explored. The interaction of hunger and satiety is responsible for providing the body with sufficient food and nutrients .

A distinction is made between a feeling of fullness and a feeling of fullness that only sets in a while after a meal. In the case of disorders of the feeling of satiety, the body’s regulatory mechanisms between hunger, appetite and satiety do not function properly or at all.

function & task

The job of feeling full is to tell the body when it has consumed enough food and nutrients. The feeling of satiety is the opponent of the feeling of hunger, which shows the body when food is needed. Food intake is regulated by the interaction of hunger and satiety. 

Control is via the hypothalamus in the diencephalon . In this area of ​​the brain, all internal and external stimuli are evaluated during food intake and messenger substances are released that tell the body that it is full. Fullness is not synonymous with being full, being full only sets in a while after a meal and describes the state after a meal until the onset of the next feeling of hunger.

In the hypothalamus there is a hunger center and a satiety center that are active at different times. Both are part of the orexic network responsible for controlling food intake. The first signals of satiety when eating are sent by the stomach when the ingested food stretches the walls of the stomach. This stimulus signal is received by the hypothalamus.

However, the satiety signal does not only come from the full stomach, but chemoreceptors also send signals to what extent nutrients have been absorbed. These receptors are located in the gut and liver .

Both signals together have an impact on the feeling of satiety and the amount of food consumed. For example, if only a large amount of low-calorie liquid is drunk, the stomach expands and reports a signal, but the chemoreceptors do not respond and there is no feeling of satiety. Conversely, it works similarly. When a small amount of food with a high nutrient density is eaten, the chemoreceptors respond because enough nutrients have been taken in, but the stomach does not because the walls have not been stretched enough.

Other satiety signals are communicated to the brain by hormones that are formed in the intestines during the digestive process, partly via the blood and partly via nerve tracts , including insulin and leptin . As soon as a variety of satiety signals are sent to the hypothalamus, it responds by releasing appetite-inhibiting substances such as serotonin .

How many factors work together in the feeling of satiety has not yet been researched. In addition to physiological influences, psychological ones probably also play a role.

Diseases & Ailments

In the case of various eating disorders such as being overweight ( obesity ), compulsive eating ( bulimia ) and cravings ( binge eating ), the interplay of hunger, appetite and satiety does not work or no longer works completely. 

Even if the causes have not been fully researched, it has been proven that in people who frequently eat large portions, the stomach walls take longer to react to the stretching. As a result, they tend to overeat. Fast eaters, on the other hand, eat so quickly that the meal is over before they even report feeling full.

In the case of overweight people, it is not entirely clear whether they are no longer sending proper satiety signals or whether they are unable to perceive them properly. Researchers suspect that frequent dieting irritates the metabolism and thus the regulation of hunger and satiety. Due to diet experiences, the body fears that it will have to create reserves for future “hunger periods” such as diets and no longer sends a feeling of satiety.

Psychological problems can also affect and significantly disrupt the balance between appetite, hunger and satiety, e.g. B. fear , anger, sadness or tension. In people with ravenous hunger pangs, such as those that occur with bulimia, binge eating, but also in some overweight people, control over hunger and satiety is completely lost. They often only stop eating when they vomit .

Psychologists see one of the causes in eating habits that are too strictly regulated, both with diets and with eating that is permanently controlled by the head. People who eat head-controlled avoid “unhealthy” foods and stop eating before satiety to save calories. As a result, the body constantly stays below the required amount of calories and, according to the psychologists, eventually fights back in the form of food cravings if control of the will is lost, e.g. B. is weakened by stress . The yo-yo effect after weight loss through dieting is an example of this.