Anorexia nervosa is an eating disorder characterized by an intense fear of weight gain, distorted body image, and excessive dieting and exercise to reduce or control body weight. People with this condition severely limit their caloric intake. It usually begins between the pre-teen years and young adulthood and occurs more frequently in women. Untreated anorexia nervosa can lead to severe, life-threatening malnutrition. ^{[1] [2]} Compared to other mental disorders, anorexia has one of the highest mortality and suicide rates.^[3]

The signs and symptoms of anorexia nervosa include certain thought patterns, behaviors, and physical characteristics. Common thought patterns include intense fear of weight gain, an obsessive and distorted view of body weight or shape, and denial of illness or health risk.

Common behaviors include refusing to eat around others, purging meals (vomiting or using laxatives or diuretics), exercising excessively, and severely restricting food intake.

The physical manifestations of anorexia nervosa are similar to those of prolonged starvation and include being underweight, sensitivity to cold temperature, dry mouth, constipation, edema (swelling) in the extremities, and mental fatigue. Over time, people with anorexia can develop lanugo, a thin coat of fine body hair that is thought to help insulate the body. Anorexia can also lead to serious complications such as cardiomyopathy, hypotension, bradycardia, osteoporosis, muscle wasting, low white blood cell and platelet counts, electrolyte-induced arrhythmias (irregular heart rhythms), kidney damage, brain atrophy, and seizures.^[1][2]

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.^[4]

Anorexia nervosa can be difficult to treat because people may deny having this illness or refuse treatment because of their fear of weight gain. The primary goal of initial treatment is to improve caloric intake to avoid the associated medical conditions related to undernourishment. People who are affected may need to work with a medical doctor, a mental health professional, and a dietitian to safely increase their food intake and avoid refeeding syndrome (a life-threatening change in electrolyte concentrations). Some extremely malnourished people with serious complications may require hospitalization.

Although some medications, like antidepressants and mood stabilizers, can be prescribed to address the underlying depression and anxiety, they don’t reduce the desire to lose weight or the harmful behaviors. Therefore, therapy with a professional trained in eating disorders is necessary to address the fears and beliefs that lead to disordered behaviors. In addition to individual therapy, family therapy and support groups can also be helpful.^[1]

A few studies have explored cannabinoids as part of a treatment plan for anorexia, but only a synthetic cannabinoid (dronabinol) led to a small amount of weight gain, whereas other substances caused adverse effects without improving weight status. Based on the current evidence, cannabinoids aren’t recommended.^[5]

Medically supervised diets play an essential role in treating anorexia nervosa. If the person is severely malnourished, they may need to be fed through a tube or intravenously to prevent the electrolyte imbalances that can occur from eating too much too quickly after a period of starvation. However, this isn’t a concern for every person, and some evidence suggests that it’s safe to rapidly increase food intake with thorough supervision to manage electrolyte levels.^[6][1]

Deep brain stimulation — which uses implanted electrodes to send electrical signals to certain brain regions — has been shown to improve psychiatric symptoms, quality of life, and weight restoration in people with anorexia nervosa. However, due to the very low number of participants, more studies are needed to confirm these preliminary results.^[7][8][1]

Intranasal oxytocin has also been studied, but it doesn't appear to have any effect on eating disorder symptoms in anorexia nervosa.^[9][10][1]

Social support and mindfulness practices can also help to improve some of the psychological symptoms of anorexia.^[11][1]

A number of factors may play a role in the development of anorexia nervosa. Genetics, hormones, and brain structure may predispose a person to developing an eating disorder. Other risk factors include perfectionism, impulsivity, mood disorders, and a negative self-image. A history of being bullied, sexually abused, or experiencing eating problems or obesity as a child could also increase the risk of anorexia.^{[12] [2]} Social media use and sociocultural beauty ideals have also been identified as potential contributing factors.^[13][1]