What is Atypical Anorexia Nervosa: Symptoms, Causes and Treatment

Eating disorders are not as black-and-white as their diagnoses may make them seem. Diagnostic criteria outline the most common symptom combinations and presentations of these disorders, however, many of those struggling with eating disorders do not display as clear-cut as this criteria.

For this reason, the Diagnostic and Statistical Manual of Mental Illness created the OSFED (Other Specified Feeding and Eating Disorder) category of diagnoses [1].

This category specifies eating disorder presentations that “cause clinically significant distress or impairment in social, occupational, or other important areas of functioning predominate but do not meet full criteria for any of the disorders in the feeding and eating disorders diagnostic class [1].”

Women Weighing Herself

Atypical Anorexia Nervosa is one of these disorders.

Atypical Anorexia Definition

Atypical Anorexia is used when an individual meets “all of the criteria for anorexia nervosa…except that despite significant weight loss, the individual’s weight is within or above the normal range [1].”

Atypical Anorexia Nervosa ICD-10 Code

The International Classification of Diseases Code allows diagnoses that may be described differently worldwide to have a universal signifier. For atypical anorexia nervosa, the ICD-10 code used is the code for “Eating Disorder, unspecified,” F50.9.

Atypical Anorexia Facts

Atypical Anorexia Nervosa is researched a great deal less than Anorexia Nervosa, however, as it becomes more prevalent, researchers are increasing their awareness of this disorder.

  • Atypical Anorexia Nervosa hospitalizations comprise nearly one-third of hospital inpatient eating disorder treatment programs [2].
  • 1 in 4 adolescents with atypical anorexia present with Bradycardia [2].
  • 1 in 3 adolescents with atypical anorexia amenorrhea [2].
  • At least 40% of those struggling with atypical anorexia nervosa require admission to a hospital [2].
  • Research indicates that psychological distress related to eating and body image is worse in atypical anorexia than anorexia nervosa [2].


Atypical Anorexia Symptoms

Many of the symptoms of atypical anorexia nervosa are similar to those of anorexia nervosa and are important to be aware of.


Individuals struggling with atypical anorexia may not appear emaciated, however, they are restricting often to the same degree as an individual with anorexia nervosa and their bodies indicate this through:

  • Significant weight loss yet being of a weight within normal limits.
  • Yellowing/drying skin.
  • Abdominal Pain.
  • Gastrointestinal issues.
  • Reduced immune system.
  • Constipation.
  • Lethargy and low energy.

Behavioral & Emotional

Atypical anorexia nervosa’s difference from anorexia nervosa exists in the distinction of their weight. As such, many of the behavioral and emotional symptoms are similar. An important difference to note, however, is that individuals with atypical nervosa may deem themselves as “not sick enough” or use their weight as a reason that they are “healthy” or “fine.” If an individual is not severely underweight, their disorder may go dangerously unnoticed. Symptoms to be aware of behaviorally and emotionally include:

  • Hyperfocus on body weight, size, and shape.
  • Low self-worth or distorted body image.
  • Intense fear of being overweight or having fat.
  • Hyperfocus on food, nutritional content, and/or bodily impact of food.
  • Refusing to eat or be seen eating by others.
  • Increased emotional dysregulation (irritability, mood swings, etc).
  • Difficulty thinking and focusing.

Long-Term Effects of Atypical Anorexia

Many assume that atypical anorexia nervosa is somehow less serious because of its “atypical” signifier. This is absolutely not the case, as it often comes with the same medical and psychological consequences of anorexia nervosa such as:

  • Damage to vital organs.
  • Bone and muscle loss/damage.
  • Reduced daily life functioning.
  • Cardiovascular complications.
  • Increased depressive symptoms and suicidal ideation.
  • Death.

Additionally, studies have found that those with atypical anorexia nervosa was considered to be “obese” weights prior to disorder development, suggesting that “with a similar duration of symptoms, they may present to clinical services before they become underweight [2].” Left untreated, the disorder would likely continue and fall into anorexia nervosa diagnostic territory. With this, come increased long-term effects.

Related Reading

Doctor talking to patient

What Causes Atypical Anorexia?

There are few studies conducted on atypical anorexia, however, some of the factors that can contribute to the disorder are known.

Biological Factors

The most notable biological factors that may lead to atypical anorexia are genetic predispositions to eating disorders and other mental illnesses. More research needs to be conducted to explore the possibility of contributing gene variants.

Psychological Factors

As mentioned above, a prior diagnosis of a mental illness makes one more susceptible to developing atypical anorexia. Other psychological factors include a tendency for perfectionism and rigidity in behaviors and beliefs. Experiencing a history of trauma also makes one more likely to develop the disorder.

Seeking Help: Atypical Anorexia Treatment Options

As mentioned above, with the small margin of difference between the two, treatments used for anorexia nervosa are often used and shown to be effective with atypical anorexia.

This means the most effective methods of treatment often involve Cognitive Behavioral Therapy, Dialectical Behavior Therapy, and Family-Based Treatment.

For those struggling with atypical anorexia nervosa, the biggest challenge is insurance coverage. Unfortunately, insurances often focus more on numbers than individual experiences. This means that insurance receiving data indicating an individual is not underweight might jeopardize their coverage of treatment.

Woman Measuring hands

Do not allow this to make you feel disconcerted, hopeless, or as if you are not “sick enough.”

Treatment centers are used to the criteria and requirements of insurance and most have a Case Manager assigned to help you communicate your need for support to your insurance and fight for your treatment.

The level of care needed for atypical anorexia depends on the severity of an individual’s disorder and a treatment center can support you in determining what level of care will be best to get you on the road to recovery.


[1] American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.).

[2] Sawyer, S. M., et al. (2016). Physical and psychological morbidity in adolescents with atypical anorexia nervosaPediatrics, 137:4.

Author: Margot Rittenhouse, MS, LPC, NCC

Page Last Reviewed and Updated By: Jacquelyn Ekern, MS, LPC on August 30, 2021