About 5% of people with anorexia die from complications over a ten-year period, a nearly six times increased risk. The term "anorexia nervosa" was first used in 1873 by William Gull to describe this condition. In recent years, evolutionary psychiatry as an emerging scientific discipline has been studying mental disorders from an evolutionary perspective. It is still debated whether eating disorders such as anorexia have evolutionary functions or if they are problems resulting from a modern lifestyle. Signs and symptoms
Anorexia nervosa is an eating disorder characterized by attempts to lose weight to the point of starvation. A person with anorexia nervosa may exhibit a number of signs and symptoms, the type and severity of which may vary and be present but not readily apparent.Anorexia nervosa, and the associated malnutrition that results from self-imposed starvation, can cause complications in every major organ system in the body. Hypokalaemia, a drop in the level of potassium in the blood, is a sign of anorexia nervosa. A significant drop in potassium can cause abnormal heart rhythms, constipation, fatigue, muscle damage, and paralysis.Signs and symptoms may be classified in physical, cognitive, affective, behavioral and perceptual:

Physical symptoms
A low body mass index for ones age and height
Amenorrhea, a symptom that occurs after prolonged weight loss, causing menstruation to stop
Dry hair and skin, as well as hair thinning
Fear of even the slightest weight gain; taking all precautionary measures to avoid weight gain or becoming "overweight"
Rapid, continuous weight loss
Lanugo: soft, fine hair growing over the face and body
Bradycardia or tachycardia.
People with anorexia are, in general, highly perfectionistic and most have obsessive compulsive personality traits which may facilitate sticking to a restricted diet. It has been suggested that patients with anorexia are rigid in their thought patterns, and place a high level of importance upon being thin.A risk factor for anorexia is trauma. Although the prevalence rates vary greatly, between 37% and 100%, there appears to be a link between traumatic events and eating disorder diagnosis. Approximately 72% of individuals with anorexia report experiencing a traumatic event prior to the onset of eating disorder symptoms, with binge-purge subtype reporting the highest rates. There are many traumatic events that may be risk factors for development of anorexia, the first identified traumatic event predicting anorexia was childhood sexual abuse. However, other traumatic events, such as physical and emotional abuse have also been found to be risk factors. Interpersonal, as opposed to non-interpersonal trauma, has been seen as the most common type of traumatic event, which can encompass sexual, physical, and emotional abuse. Individuals who experience repeated trauma, like those who experience trauma perpetrated by a caregiver or loved one, have increased symptom severity of anorexia and a greater prevalence of comorbid psychiatric diagnoses.In individuals with anorexia, the prevalence rates for those who also qualify for a PTSD diagnosis ranges from 4% to 52% in non-clinical samples to 10% to 47% in clinical samples.