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Eating Disorders

Why Atypical Anorexia Is So Often Missed

This deadly eating disorder is hard to detect, and it’s becoming more common.

The challenge with atypical anorexia nervosa (AAN)—both for providers trying to assess it and for people wondering if they have it—is its presentation. People with AAN have all the same symptoms as people with “regular” anorexia except one: They’re not underweight. So it can go unnoticed, sometimes for years.

Even when people with AAN look in the mirror, or visit their doctor, anorexia is often not suspected. “How could I have anorexia?” thinks the person who has it. “I need to lose weight.”

At an office visit, the doctor too often agrees. Unless he or she takes the time to ask the right questions, listens carefully to the answers, and does a thorough workup that includes blood tests and other labs, the diagnosis is missed.

That miss can go on for a long time. A recent study found that the average length of time a person lives with AAN before they’re officially diagnosed with it is 11.6 years. That's a lot of needless suffering.

During my career as a psychiatrist (my specialty is addiction), it has been rare to come across a psychological disorder—atypical anorexia in this case—that is at once (1) relatively common, probably more than we realize; (2) extremely serious and sometimes deadly; and (3) so little studied or understood.

Given all that, consider this article a small part of a much-needed awareness campaign for AAN.

The Basics of Atypical Anorexia

People of all genders, shapes, and sizes can develop AAN, and the number of people diagnosed with it is growing.

Causes and risk factors

AAN can have multiple causes, including genetic, biological, psychological, social, and cultural ones. People are more likely to develop AAN if they’re struggling with mental illnesses such as anxiety, depression, bipolar disorder, or substance use. Personality traits associated with AAN include:

People with AAN are often highly affected by social and cultural messages that say a certain body type is better than others. When they keep hearing what their body should look like, people at higher risk of AAN start taking drastic measures to get there. This may include extreme diets, purging, or excessive exercising.

Many with AAN have a history of dieting, being overweight, or being teased about their weight. One study found that 70 percent of patients with AAN had been overweight or obese in the past, while only 12 percent of people with "regular" anorexia had been overweight or obese.


The symptoms of AAN are similar to regular anorexia, including a severe restriction of daily food intake, and engaging in behaviors to avoid weight gain such as dieting, fasting, or excessive exercise. Other symptoms may include:

  • Intense fear of gaining weight or being overweight
  • The desire to change one's weight or body shape at any cost
  • A distorted or negative body image
  • Hyperfocus on food, nutritional content, or the impact that food has on the body
  • Refusing to be seen eating by others

Physical complications

Again, these mimic the complications of standard anorexia. They include:

  • Low blood pressure
  • Fragile bones
  • Brittle hair and nails
  • Fine hair growing all over the body (lanugo)
  • Bradycardia (unusually slow heart rate)
  • Hormone changes or reproductive health issues, including amenorrhea
  • Severe constipation

Please note that the medical status of patients with atypical anorexia can be as bad, if not worse, than patients with standard anorexia. Even if they appear to be normal weight or overweight, if they lose a significant amount of weight in a short amount of time, many people will experience symptoms of malnutrition.


This is important: AAN is treatable. People can get better with a combination of talk therapy, nutritional education, medications, and general medical care. Most people can be treated in an outpatient setting, meaning they live at home and visit their provider(s) as needed. The goal is to address any mental and physical health needs, get stabilized at a healthy weight, and slowly return to regular eating patterns.

Regular Anorexia vs. Atypical Anorexia: A Case Study

To better understand the difference between the two disorders, consider a hypothetical case of two 16-year-old girls who have anorexia. The first is 5’4” and used to weigh 120 pounds—normal for her height. She now weighs 85 pounds after a year of intensive exercising and highly restrictive eating.

Despite all that, she still believes she’s fat. She has bradycardia (low heart rate) and stopped menstruating about six months ago. This is classic anorexia, which her doctor recognizes the moment she arrives for her annual checkup.

The other 16-year-old is also 5’4” but used to weigh 170 pounds. After six months of crash dieting and exercising, sometimes for two or more hours a day, she lost 50 pounds and now weighs 120—a normal weight for her age and height.

But because she lost so much weight so quickly, she is medically unstable with bradycardia and other issues and has stopped having her period. When she comes in for her annual checkup, the doctor at first doesn’t suspect atypical anorexia, even though this person is seriously ill. Only later, after a thorough exam, lab tests, and several empathetic but thorough questions does the diagnosis become clear and a treatment plan is provided.

Recent Research Shows the Challenges We Face

A 2020 analysis out of the University of Washington in Seattle looked at the experience of patients seeking treatment for AAN. It did not paint a pretty picture. The following are four key findings from the review:

  1. AAN is a serious illness with similar life-threatening medical complications to AN, including electrolyte imbalance, clinically low heart rate and blood pressure, and hypothermia.
  2. Healthcare providers often failed to recognize AAN in normal and higher-weight patients.
  3. Higher-weight patients with AAN were often counseled to lose weight despite exhibiting clear eating disorder behaviors. This recommendation put them at further health risk.
  4. The weight stigma shown by providers resulted in patients living for longer periods with undiagnosed, untreated AAN. In some cases, provider weight stigma led to triggering or re-triggering ED behaviors in their patients.

Final Thoughts on Atypical Anorexia

I return to my goal with this article, which is to shine a light on this insidious disorder. It is real, it is deadly, and it is likely more common than we know. At this point, providers are not doing a good job of recognizing it in their patients. That needs to change as soon as possible.


Sawyer S.M., Whitelaw M., Le Grange D., Yeo M., & Hughes E.K. (2016). Physical and psychological morbidity in adolescents with atypical anorexia nervosa. Pediatrics.

Harrop, E. (2020). “Maybe I Really Am Too Fat to Have an Eating Disorder”: A Mixed Methods Study of Weight Stigma and Healthcare Experiences in a Diverse Sample of Patients with Atypical Anorexia. University of Washington Ph.D. thesis.

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