According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), an anorexia nervosa diagnosis requires being significantly underweight (body mass index less than 18.5) due to restricting food or purging meals, having an intense fear of weight gain, and having a distorted body image. Prior versions of the diagnostic criteria also included amenorrhea (lack of a natural menstrual period), but this is no longer required for a diagnosis.[1]
Because anorexia nervosa is a mood disorder that can also lead to physical symptoms, a person might need to see both a medical doctor and a mental health professional to rule out other causes of the physical symptoms and confirm the diagnosis.[2]