Orthorexia nervosa is an unhealthy obsession with eating only what a person perceives as "healthy," which can lead to social and psychological issues, including health anxiety and obsessive-compulsive symptoms. It is characterized by rigid dietary rules and avoidance of certain foods, and although it was first identified in 1997, it is not yet officially classified as a disorder in the DSM-5.

The main signs and symptoms of orthorexia nervosa include obsessive thoughts and behaviors related to food, particularly a fixation on "healthy" eating and strict dietary rules that lead to psychological distress and affect daily life. This condition can result in extreme anxiety over food choices, potential weight loss, and nutritional deficiencies, but it is not primarily driven by a desire for thinness.

Orthorexia nervosa is not an established clinical diagnosis and is not included in the DSM-5, and any potential diagnosis relies on patient history and clinical judgment. The current diagnostic questionnaires have significant limitations and often fail to differentiate between orthorexia nervosa and healthy eating habits, which highlights the need for further research to validate the diagnosis and develop accurate diagnostic tools.

There are currently no specific medical treatments for orthorexia nervosa because the condition is still being defined; however, treatment may involve approaches similar to those for anorexia nervosa and obsessive-compulsive disorder. The focus is on increasing food variety, addressing disordered thoughts about food, and restoring nutritional status, potentially via cognitive behavioral therapy, family therapy, nutrition counseling, and medications.

No supplements have been studied specifically for orthorexia nervosa.

Research on orthorexia nervosa is still in its early stages and primarily concentrates on defining the condition and creating diagnostic tools. As a result, there is currently limited research available on treatments for orthorexia nervosa.

The causes of orthorexia nervosa are not fully understood and are likely complex; they potentially involve genetics, personal or family history of dieting, personality traits, mental disorders, social media use, and experiences of bullying. More research is needed to gain a clearer understanding of its causes.