Anorexia Nervosa

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Anorexia nervosa is an eating disorder characterized by refusal to maintain a healthy body weight and an obsessive fear of gaining weight, often coupled with a distorted self image which may be maintained by various cognitive biases that alter how the affected individual evaluates and thinks about her or his body, food and eating. Persons with anorexia nervosa continue to feel hunger, but deny themselves all but very small quantities of food. The average caloric intake of a person with anorexia nervosa is 600-800 calories per day, but in extreme cases self-starvation is more extreme. It is a serious mental illness with a high incidence of comorbidity and the highest mortality rate of any psychiatric disorder.

It can affect men and women of all ages, races, socioeconomic and cultural backgrounds. Anorexia nervosa occurs in the ratio of 1:10 in males:females.

The term anorexia nervosa was established in 1873 by Sir William Gull, one of Queen Victoria's personal physicians. The term is of Greek origin: an- (ἀν-, prefix denoting negation) and orexis (ὄρεξις, "appetite"), thus meaning a lack of desire to eat.

 A person with anorexia nervosa may exhibit a number of signs and symptoms, some of which are listed below. The type and severity vary in each case and may be present but not readily apparent. Anorexia nervosa and the associated malnutrition that results from self-imposed starvation, can cause severe complications in every major organ system in the body.

It should be noted that some of the possible signs listed below (Russell's sign, scarring of knuckles, purging/self-induced vomiting and use/abuse of laxatives, diet pills, i.e., and swollen cheeks/enlargement of the salivary glands) are signs primarily of bulimia, which is a condition that often occurs simultaneously with anorexia.

Studies have hypothesized that the continuance of disordered eating patterns may be epiphenomena of starvation. The results of the Minnesota Starvation Experiment showed that normal controls exhibit many of the behavioral patterns of anorexia nervosa when subjected to starvation. This may be due to the numerous changes in the neuroendocrine system, which results in a self perpetuating cycle.^{[46][47][48][49]} Studies have suggested that the initial weight loss such as dieting may be the triggering factor in developing AN in some cases, possibly due to an already inherent predisposition toward AN. One study reports cases of AN resulting from unintended weight loss that resulted from varied causes such as a parasitic infection, medication side effects, and surgery. The weight loss itself was the triggering factor. 

source:wikipedia