Orthorexia, or orthorexia nervosa is a term coined by Dr. Steven Bratman, a Colorado MD, to denote an eating disorder characterized by a fixation on eating what the sufferer considers to be healthful food, which can ultimately lead to early death.
Bratman coined the term in 1997 from the Greek orthos, "correct or right", and orexis for "appetite". Literally "correct appetite", the word is modeled on anorexia, "without appetite". Bratman describes orthorexia as an unhealthy obsession with what the sufferer considers to be healthy eating. The subject may avoid certain foods, such as those containing fats, preservatives, or animal products, and suffer malnutrition. Dr. Bratman asserts that "emaciation is common among followers of certain health food diets."
According to the Macmillan English Dictionary, the word is entering the English lexicon, though the psychiatric community has not widely recognized the condition and it is not listed in the DSM-IV. Bratman's concept has been criticized by some who feel that focusing on healthful diet is generally beneficial and does not indicate a pathology, while it has been supported as a diagnosis by some practitioners who state they have seen the damaging results of the condition in their practices

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http://en.wikipedia.org/wiki/Orthorexia