There are no reliable statistics concerning the number of people with eating disorders because:

• Many people are ashamed and don't want to talk about it. Sometimes they are not even aware of their problem. This is similar to the situation with alcohol, where also many people are not aware that they have a problem.
• Doctors sometimes treat illnesses caused by eating disorders without realizing that the patient suffers from an eating disorder.
• Probably only about ten percent of those with eating disorders get a proper diagnosis and treatment. On the average there is a delay of about eight years before the start of an eating disorder and medical recognition and treatment of the disorder.
• There are typical cases such as extreme anorexia or compulsive eating, and there are many intermediate ones. Overweight may be caused by eating disorders but also by other reasons. Psychological factors may even be involved so that similar treatment as for eating disorders can help also for obesity in these cases.

Investigations of the incidence of eating disorders are usually done on small groups of one or a few hundred people, and results vary widely. The number of people with pronounced eating disorders have in different investigations been estimated to be between a few percent and less than one percent. The higher figure is probably more accurate. Some investigations find symptoms of bulimia in 10 % of all young women, other investigations find such symptoms in between 20 % and 35 %. Of all people with eating disorders, different investigations estimate that between 90 % and 95 % are women. Why is this? . One investigation found only 70 % to be women, but that investigation deviates from most others. Symptoms of anorexia are by different investigations found in between 0,5 % and 1,0 % of teenage girls. One study reported that more than 10 % of all young women have some kind of eating disorder, even if it does not always fit into any of the standard categories of anorexia and bulimia. The number of people who are overweight have in different investigations been estimated to be between 15 % and 60 % of the population. More. Other reports, see also and see also .

Eating disorders can in exceptional cases be fatal, such as death by starvation. Obesity increases the incidence of many diseases, and also increases the risk of death through multiple diseases. Even for those who survive, the eating disorder often causes much distress. According to one investigation, 60 % of people with anorexia and 40 % of people with bulimia were feeling unwell. Common side effects of eating disorders are kidney problems, stomach problems, teeth problems, malnutrition and distorted nutrition balance. Psychiatric side effects can be alcoholism, drug abuse and suicide. In one study of patients with Anorexia, 15 % died within 12 years because of suicide, infections, stomach problems or malnutrition.