For people without eating disorders and who have a well working hunger and satisfaction capability, the intake of nourishment is perfectly regulated so that they will be satisfied at the right time. When they have eaten enough, eating more does not feel desirable, they feel happy and satisfied.

Satisfaction is a sensation which the brain creates by combining different signals, like signals about the blood sugar level, signals about how much food is in the stomach, knowledge about what they have eaten and what they need, etc. There is, for example, enterostatin, a peptide created by the enzyme procolipas and which is produced when fat is separated in the intestines. This peptide sends signals to receptors saying "this is enough". The opiate system which controls feelings of wellbeing is restrained so that the reward centers in the brain are not any more stimulated.

For normal people, the brain combines all these factors to conclude that they are not hungry any more. For a person with eating disorders, this function either does not work at all, or works only partially. Some often have a correct feeling of satisfactions, but ignore it.

Here are some reasons why some people do not feel satisfied when other people are:

• A person who has recently been on a diet, or who has eaten and vomited, may get signals from the body saying: "Help, this is a famine, it is best to eat while there is food. You never know when you can get food again."
• Food, which people ate in former times like root vegetables, porridge, meat, fish, etc. gives more feeling of satisfaction than food which people eat today like biscuits, chips, soft drinks, candy, white bread, sugar, etc.
• People who eat rapidly will take in much more food, before they are satisfied, than people who eat slowly, one piece at the time, put down their fork and knife between each bite and chew thoroughly.
• Food reduces anxiety. A person who is agitated and nervous may want to reduce the anxiety with food, and this wish may be larger than their capacity of recognizing satisfaction.
• Many people with eating disorders are not conscious of their hunger and satisfaction sensations. They cannot react to a sensation which they are not conscious of. The offers of the table will win.

  Such people cannot separate hunger and other disagreeable feelings like anger, fear, tiredness or aversion. All of these feelings will to them be experienced as hunger. People who cannot distinguish different sensations may get eating disorders.