Hunger and appetite

You should have a meal only when you are really hungry and stop eating before you feel full.

Hunger, appetite, and satiation are all sensations that have no direct association with either a particular body part or organ. However it is their influence that triggers the motivations regulating our eating behavior–how often and what, specifically, we eat. If we would only eat when we are actually hungry and, then, only eat until we are half full, the problem of obesity would not be as widespread.

Hunger is the sensation generally characterized by spasms in an empty stomach and the instinctive need for food. Hunger is initiated when the body’s food reserve drops below the level of normal energy balance. Thus, hunger is nothing but a physiological regulator for the amount of food intake. In most cases, contractions of the empty stomach significantly increase hunger. These contractions are perceived by the nerve endings (i.e. mechanoreceptors) in the wall of the stomach and conveyed to the brain, where the feeling of hunger originates. This mechanism is exploited in some surgical weight-loss methods, when the stomach volume is surgically reduced by bandaging or implanting a temporary bubble in to the gastric cavity. Additionally, diets recommended by some dietitians that involve large quantities of low-caloric and fiber-rich foods that can occupy significant portions of the stomach have been observed to eliminate gastric-induced hunger.

Blood glucose level is also an important contributing factor to the sensation of hunger. Glucose levels that drop below a critical concentration are intimately associated with the feeling of a hungry stomach, i.e. strong contractions of its muscular tissue.

Available evidence proves that the intensity of the sensation of hunger may depend on the ambient temperature. In humans, as well as in other warm-blooded animals, the quantity of ingested food is in inverse proportion to the ambient temperature. This is a direct result of the body’s thermoregulation system and is partly responsible for increasing hunger after long exposures in cold weather. It is important to note that the thermoregulation system is triggered by the temperature of the direct environment and not the weather. That is in a well-heated home during winter time the thermoregulation system, and thus hunger, are affected by the room-temperature within the home and not, for example, the sub-zero temperature outside.

Appetite is an emotional sensation associated with the desire to eat certain food. It is based on the pleasure you experience while eating a particular food. As opposed to hunger, appetite may occur even when food reserves are sufficient. Appetite can occur while feeling hungry or by itself. It is one of the psychological factors necessary for the control of food intake.

The palatability of a particular foodstuff, such as taste, smell, consistence and amount, mostly depend on our personal attitudes. Therefore the weight-loss methods which consider psychological attitudes towards food show the highest efficacy in regulating nutrition.

Satiation (‘sense of fullness’) is the disappearance of the sensation of hunger caused by consuming food. As a matter of fact, it is the opposite of hunger and appetite. Satiety, however, is more than mere absence of hunger, since it can be associated with pleasure and the feeling of a full stomach. One may distinguish between two kinds of satiation, that is, early or partial satiation that occurs before absorbing and utilizing the ingested food, and late or complete satiation after its absorption. This distinction explains why it is ideal, physiologically, to stop eating when early satiety is achieved.

A dieter may be encouraged to stimulate early satiation in order to prevent overeating. The following are a few suggestions to increase the chances of attaining early satiation:

• Avoid eating your meals in a hurry, chew the food well;
• Avoid distractions such as conversations, TV or other things that may affect normal satiation;
• Eat in small bits, chewing every mouthful at least 32 times;
• Ensure that the table is well-laid with nice-looking, fragrant food;
• Some experts recommend having a meal to your favorite light music.

All of the points above contribute to obtaining early satiation and help control one’s appetite in accordance with one’s true energy requirements.

Full satiation is obtained only when nutrients levels (such as glucose) in the blood increase; i.e. after the taken food is mainly absorbed. Hence, hunger and satiation are nothing but two sides of the same coin. Moreover, apart from the factors mentioned above, the brain is highly influential in controlling these feelings. In several parts of brain there are complex structures responsible for the control of appetite. The hunger and satiety centers in the brain have been located in the hypothalamus and corresponding formations in the limbic system and the cortex of cerebrum.

In most individuals, the amount of food intake increases or decreases in accordance with their energy expenditure. Thus, the sensations of hunger, appetite and satiety are efficient in regulating one’s eating pattern. However, in those who are obese this form of regulation is not enough. It is necessary to have a strong will to lose weight in order to get rid of unhealthy eating habits and change one’s nutrition. Nevertheless, this is the only way to regulate one’s appetite.

Most modern drugs that decrease appetite and claim to help you lose weight affect the hunger and satiety centers. Taking these medications, which are called anorectic, outside of medical supervision is likely to cause significant changes in brain function and may have serious side-effects. Therefore, only a physician should prescribe and administer these drugs.

Anorexia is the absence of the sensation of hunger even when a normal individual would experience hunger as a result of a blood level drop of necessary nutrients. Severe anorexia is likely to result from self-treatment with anorectic drugs, and these patients may starve to death even when nutritious foodstuffs are available.

It is more reasonable and safe to regulate one’s appetite by using psychological correction techniques that influence the psychological aspect of nutrition. However, there are certain cases, such as cerebral disorders or secondary obesity, when it is justified to administer medicines that affect cerebral centers that control hunger and satiety. Medications prescribed to suppress hunger are efficient when overeating is out of control, and cannot be overcome, thus leading to excessive obesity. These drugs are mainly used by bulimic individuals with a hypertrophied sensation of hunger.

Bulimia (binge eating) as opposed to anorexia is an eating disorder, characterized by the absence of the feeling of satiety after a meal and the persistent sensation of hunger independent of the quantity of food ingested. Bulimics consume food in order to avoid the unpleasant feeling of hunger. They develop an addiction to food, similar to a drug or alcohol addiction. This behavior is likely to result in obesity. Increased appetite and binge eating are not necessarily dangerous in isolation. However, bulimia is a condition where the patient eats almost twenty-four hours a day, with only small intervals required for sleeping and toilet. This disease is not very common and it can be cured without any medication if the affected individual is strongly motivated and able to change his eating patterns and increase physical exercise.

Among the many causes of obesity, the primary reason is unbalanced nutrition, where excessive calorie intake originates from an unhealthy choice of foodstuffs. This is a case where the individual has a normal appetite, a normal sensation of hunger and satiety, but consumes a diet that is disproportionately calorie-rich.