Orthorexia nervosa (also known as orthorexia) is a proposed eating disorder or mental disorder characterized by an extreme or excessive preoccupation with avoiding foods perceived to be unhealthy. The term orthorexia derives from the Greek ορθο- (ortho, "right" or "correct"), and όρεξις (orexis, "appetite"), literally meaning 'correct appetite', but in practice meaning 'correct diet'. It was introduced in 1997 by Steven Bratman, M.D., to be used as a parallel with other eating disorders, such as anorexia nervosa. Orthorexia is not mentioned in the widely used DSM[a], but was coined by Bratman who claims that in rare cases, this focus may turn into a fixation so extreme that it can lead to severe malnutrition or even death. Even in less severe cases, the attempt to follow a diet that cannot provide adequate nourishment is said to lower self-esteem as the orthorexics blame themselves rather than their diets for their constant hunger and the resulting cravings for forbidden foods. 
In 2009, Ursula Philpot, chair of the British Dietetic Association and senior lecturer at Leeds Metropolitan University, described people with orthorexia nervosa to The Guardian as being "solely concerned with the quality of the food they put in their bodies, refining and restricting their diets according to their personal understanding of which foods are truly 'pure'." This differs from other eating disorders, such as anorexia nervosa and bulimia nervosa, whereby people focus on the quantity of food eaten.
Steven Bratman coined the term "orthorexia nervosa" in 1997 from the Greek orthos, meaning "correct or right", and orexis, meaning "appetite". Literally "correct appetite", the word is modeled on anorexia, meaning "without appetite", as used in definition of the condition anorexia nervosa. Bratman describes orthorexia as an unhealthy fixation with what the individual considers to be healthy eating. The subject may avoid certain unhealthy foods, such as those containing fat, preservatives, man-made food-additives, animal products, or other ingredients considered by the subject to be unhealthy. If the sufferer does not eat appropriately, malnutrition can ensue. Bratman claims orthorexia sufferers have specific preferences about the foods they are eating and avoiding. Products that are preserved with additives can be considered dangerous. Industrial products can be seen as artificial, whereas fruits and vegetables can be seen as healthy. Bratman asserts that "emaciation is common among followers of certain health food diets, such as rawfoodism, and this can at times reach the extremes seen in anorexia nervosa." In addition, he claims that "anorexic orthorexia" can be as dangerous as anorexia. However, he states, "the underlying motivation is quite different. While an anorexic wants to lose weight, an orthorexic does not desire to become thin but wants to feel pure, healthy and natural. Eating disorder specialists may fail to understand this distinction, leading to a disconnect between orthorexic and physician."
Although orthorexia is not recognized as a mental disorder by the American Psychiatric Association, and it is not listed in the DSM-5, it is still used as a diagnosis by some practitioners who have documented the damaging results of the condition as they have seen in their practices.
As of January 2007, only two peer-reviewed studies have been published on the alleged condition. In the studies, Donini et al. define orthorexia nervosa as a "maniacal obsession for healthy foods" and propose several diagnostic criteria. Sufferers of orthorexia often display symptoms consistent with obsessive-compulsive disorder and have an exaggerated concern with healthy eating patterns. Like anorexia, however, these obsessive compulsive symptoms may be an effect of starvation rather than a cause of the disorder. A diagnostic questionnaire has been developed for orthorexia sufferers, similar to questionnaires for other eating disorders. Bratman proposes an initial self-test composed of two direct questions: "Do you care more about the virtue of what you eat than the pleasure you receive from eating it?... Does your diet socially isolate you?" Other questions concerning those who may be suffering from orthorexia provided by Davis on the WebMD (2000) website are: Do they spend more than 3 hours a day thinking about healthy foods? When they eat the way they're supposed to, do they feel in total control? Are they planning tomorrow's menu today? Has the quality of their life decreased as the quality of their diet increased? Have they become stricter with themselves? Does their self-esteem get a boost from eating healthy? Do they look down on others who don't eat this way? Do they skip foods they once enjoyed in order to eat the "right" foods? Does their diet make it difficult for them to eat anywhere but at home, distancing them from family and friends? Do they feel guilt or self-loathing when they stray from their diet? If yes was answered to two or more questions, the person may have a mild case of orthorexia.
Symptoms and theory
Orthorexia nervosa is characterized by an obsession with avoiding foods perceived to be unhealthy. It is important to differentiate between healthy individuals who choose specific diets for any number of reasons, and those who exhibit obsessive compulsive behavior that leads to an unhealthy condition or lifestyle. What tips the balance from being committed to healthy eating and having orthorexia is the extreme limitation and obsession in food selection. Orthorexics find themselves being unable to take part in everyday activities. They isolate themselves and often become intolerant of other people's views about food and health. This obsession for healthy foods could come from a number of sources such as family habits, societal trends, economic problems, recent illness, or even just hearing something negative about a food type or group, which then leads them to ultimately eliminate the food or foods from their diet.
ON seems to be more common in men than in women and in those with a lower level of education.
There has been no investigation into whether there may be a biological cause specific to orthorexia nervosa. However, Donini et al. link orthorexia to a food-centered manifestation of obsessive compulsive disorder, which has a lot to do with control. A 2013 study of college students found that orthorexia severity was negatively associated with self-reported executive functioning. This means that the better the student did with cognitively complex tasks, including planning and decision-making, the less likely the student was to have orthorexia.
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