Orthorexia nervosa (also known as orthorexia) is a proposed eating disorder characterized by an excessive preoccupation with eating healthy food. The term was introduced in 1997 by American physician Steven Bratman, M.D. He suggested that some people's dietary restrictions intended to promote health may paradoxically lead to unhealthy consequences, such as social isolation, anxiety, loss of ability to eat in a natural, intuitive manner, reduced interest in the full range of other healthy human activities, and, in rare cases, severe malnutrition or even death.

In 2009, Ursula Philpot, chair of the British Dietetic Association and senior lecturer at Leeds Metropolitan University, described people with orthorexia nervosa 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, where those affected focus on the quantity of food eaten.

"Orthorexia nervosa" is not recognized as an eating disorder by the American Psychiatric Association, and so is not mentioned as an official diagnosis in the widely used Diagnostic and Statistical Manual of Mental Disorders (DSM).
https://en.wikipedia.org/wiki/Orthorexia_nervosa