According to Wikipedia:
"Orthorexia, or orthorexia nervosa is a term coined by 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 describes orthorexia as an unhealthy obsession (as in obsessive-compulsive disorder) with what the sufferer considers to be healthy eating. The subject may avoid certain foods, such as those containing fats, preservatives, animal products, or other ingredients considered by the subject to be unhealthy; if the dietary restrictions are too severe or improperly managed, malnutrition can result. Bratman asserts that "emaciation is common among followers of health food diets."
I think the emaciation that Bratman speaks of is actually called anorexia.
I also think if we had a safe, clean and whole foods based system, these types of coined terms wouldn't be unnecessary. People are suffering from this because they are unhealthy from eating processed foods, refined sugars and red meat. If this is a true eating disorder, I have to say that I am a sufferer.
Instead of addressing the concerns of why these afflicted individuals are so concerned, lets just prescribe a pharmaceutical drug to mask the symptoms. I'm sure Merck could come up with something. In the mean time make sure you pick up Dr. Bratman's new book: Health Food Junkies. I'm sure he would appreciate it. I'm not buying it. The book, or the disorder.
An article on ABC news tells you more.