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Appetite

life science Maturity 11-13 Next article →

Appetite is the desire to eat food. It is very important for all higher life-forms. This feeling helps living things get enough energy to stay healthy. This energy is needed to meet metabolic needs. Sometimes, seeing tasty food can make you feel hungry. This can happen even if your stomach is not empty.

Piece of chocolate cake on a white plate decorated with chocolate sauce
Piece of chocolate cake on a white plate decorated with chocolate sauce

Appetite is controlled by a group of parts working together. These parts include the brain, the digestive tract, and adipose tissue. Adipose tissue is the body fat that stores energy. Two main signals called hormones help manage this process. Ghrelin is a hormone released from the stomach. It sends a signal to the brain to make you feel hungry. Leptin is a hormone released from body fat cells. It sends a signal to the brain to make you feel full or satisfied.

Piece of chocolate cake on a white plate decorated with chocolate sauce
Piece of chocolate cake on a white plate decorated with chocolate sauce

Sometimes, the way the body handles these signals changes. If a person has a very low desire to eat, it is called anorexia. If a person has a very high urge to eat, it is called polyphagia. These changes can be caused by many different things. Physical issues like infections or diseases can lower appetite. Stress and mental disorders can also change how much someone wants to eat. Even the way food tastes or smells can change the feeling. For example, a bad taste is called dysgeusia. Some children are picky eaters. This happens to about 25% of children.

Piece of chocolate cake on a white plate decorated with chocolate sauce
Piece of chocolate cake on a white plate decorated with chocolate sauce

Scientists have studied how genes and chromosomes affect appetite. In the 1950s, researchers discovered Prader–Willi syndrome. This is a type of obesity caused by changes in chromosomes. This discovery showed that appetite can be linked to our DNA. Some eating disorders are also more common in females than males. This suggests a possible link to the X-chromosome. Other issues come from how the brain receives signals. In some cases of obesity, the brain stops responding to leptin. This happens when there is too much body fat. The brain becomes resistant to the hormone. This can cause an appetite that feels impossible to satisfy.

Piece of chocolate cake on a white plate decorated with chocolate sauce
Piece of chocolate cake on a white plate decorated with chocolate sauce

There are many different names for eating disorders. Anorexia nervosa involves a fear of gaining weight and eating very little. People with this disorder may also exercise in a ritualistic way. Binge eating disorder, or BED, involves eating too much in short times. This can happen to children, but it is most common in adults. Studies show that the heritability of BED in adults is about 50%. Some people may also use purging to deal with food. This can include vomiting or taking purgatives.

Piece of chocolate cake on a white plate decorated with chocolate sauce
Piece of chocolate cake on a white plate decorated with chocolate sauce

Doctors use different tools to help manage appetite. Some medicines are used to suppress appetite to help with weight loss. Early medicines included fenfluramine and phentermine. Other drugs like sibutramine were later removed from the market. This was because they caused risks to the heart. Another drug called rimonabant was also removed. It was linked to worsening depression. There are also medicines used to increase appetite. In the United States, three approved agents are megestrol acetate, oxandrolone, and dronabinol. Researchers are also looking at ghrelin as a way to help. They are even studying a Japanese medicine called Rikkunshito.

Piece of chocolate cake on a white plate decorated with chocolate sauce
Piece of chocolate cake on a white plate decorated with chocolate sauce
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