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Understanding Atypical Anorexia Nervosa

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Most people are familiar with anorexia nervosa, an eating disorder in which a person avoids eating and other caloric intake in an attempt to lose weight, even though they may be severely emaciated already. 

Normally, when asked about the symptoms of anorexia nervosa, the common reply will describe a person who is thin, ill and malnourished. However, recent studies are revealing that there’s another kind of anorexia nervosa. 

Atypical anorexia nervosa mostly involves adolescents who have lost a significant amount of weight but are not thought to be medically underweight. 

Although it’s not well-known atypical anorexia nervosa is indeed an eating disorder, teenagers who’ve developed the disorder often do not show outward signs of serious medical complications related to anorexia nervosa and other eating disorders. Because of this, medical tests like blood work should be performed to ensure physical complications are addressed as well as emotional and psychological ones.

Atypical anorexia nervosa (AAN) is also known as a subtype of Other Specified Feeding or Eating Disorder (OSFED). These subtypes of other major eating disorders are listed in the DSM-V. These OSFED disorders include AAN, low-frequency bulimia nervosa, limited binge eating disorder, purging disorder and night eating syndrome, among others.

What are the symptoms of atypical anorexia nervosa?

The DSM-5 lists AAN as an eating disorder which matches the criteria for standard anorexia nervosa except for that significant weight loss. The dietary restrictions and other disordered behaviors seen in people with atypical anorexia nervosa don’t result in the severe weight loss or emaciation found on more traditional anorexia nervosa.

Additionally, adolescents with AAN will display the same types of cognitive distortions and disordered behaviors associated with mainstream anorexia nervosa. Physical complications experienced by AAN patients are similar to complications diagnosed in anorexia nervosa sufferers, but not as extreme and often less obvious.

It’s not unknown for adolescents with atypical anorexia nervosa to be considered medically overweight, although their nutritional balance is skewed. 

This unexpected symptom, among others, has led clinicians to apply the “atypical” tag to this disorder.

In cases of anorexia nervosa, as well as bulimia nervosa and other commonly-known eating disorders, it’s extremely common for the individual to deny they have an eating disorder. This is the case for AAN as well.

When the subject of an eating disorder is raised, people with AAN might flat out deny the accusation, try to represent it as a ‘normal’ diet, lash out at family and friends for picking on them or blame stress for their eating disorder (relationship, career, school, etc). A direct confrontation may backfire, as AAN sufferers who’ve been confronted may go to great lengths to conceal their eating disorder.

Can AAN be diagnosed by a doctor?

The friends and family of teenage AAN patients, and the individuals themselves, often do not realise they have a serious eating disorder because of the absence of severe weight loss normally related to anorexia nervosa. Because they aren’t emaciated or malnourished, they may not think there is any significant problem. Lack of knowledge about atypical anorexia nervosa can prevent parents and teens from seeking out professional anorexia nervosa treatment.

Since significant weight loss is not the defining factor for AAN, laypeople may have difficulty noticing that there’s a problem. However, most family doctors are capable of determining if further investigation, or a psychiatric or psychological assessment, is necessary.  They might be able to make the initial diagnosis themselves.

Once the possibility of the disorder has been raised, there are anorexia nervosa treatment centres that specialise in making a full diagnosis, including AAN, bulimia nervosa, binge eating disorder, and orthorexia nervosa.

If you observe obsessive-compulsive behaviours involving food restriction, counting calories, counting fat grams, or other disordered behaviours like food rituals during meals, you should consider reaching out to your doctor and a local treatment center to get started on recovery.

 *** Image credit: Freepik


Carrie Hunnicutt has over 20 years of behavioural health business development experience. 

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