PWS is caused by a chromosomal defect. It is non hereditary and it affects both sexes and all races. PWS can bring with it a number of symptoms including motor skill deficiency, incomplete growth, and mental retardation. In addition, PWS causes an unquenchable appetite. Left unchecked, sufferers can literally eat themselves to death. Treatment includes growth hormone and a low-cal diet that absolutely must be maintained. A fictionalized account of Prader-Willi was seen on the show CSI in 2005.

Pica is perhaps the most interesting disease on this list. It is both an eating disorder and a psychiatric problem. People with pica feel a compulsion to eat non-nutritional and non-food items. These can include anything from cigarette butts to paint. It is quite easy to get sick or even die from pica as the sufferer can eat dangerous chemicals or sharp objects that can puncture their vital organs.

While BDD can be diagnosed without the presence of an ED, is is nearly almost diagnosed along with the big two and often lingers long after other symptoms have lessened. People with BDD are convinced they have any number of defects, including but not limited to being fat and ugly,and having bad hair, bad teeth, and a bad odor. This goes beyond the normal teenage insecurities about how someone looks. When a BDD sufferer looks in the mirror, they see something completely different than those around them do.

Guess what is at number one?

Spoiler

1

Anorexia Nervosa

Newest studies estimate that 1 out of 100 teenage girls suffer from anorexia. Girls as young as 8 have been hospitalized with the condition. Brain mapping of those with anorexia shows their addiction to not eating is just as great as those with heavy drug or alcohol addiction. Anorexics are at great risk for relapse because anorexia and other eating disorders, like most addictions, never go away. Those that have been through treatment and no longer show symptoms or signs of their condition are considered in remission and must keep their impulses and urges in check. Even years down the line, one event can re-trigger the illness. However, those who do manage to keep the disease in line can recover fully and live and eat normally.

See the others here