Eating disorders do not work in the same way for everybody. The disorders may often include several different combinations of symptoms which are difficult to explain. A lot has been written about conflicting theories concerning cause, prevention and effective treatment. It is only possible to understand many symptoms by considering an individual's personal life history. The symptoms are often not directly connected with the development of eating disorders.

What is common for all eating disorders, is that the individual doesn't just eat from the need for nutrition. Starvation or excessive eating is often used in order to achieve something else: a slim body, or the reduction of anxiety, stress, anger, monotony, depression etc.