What is Anorexia Nervosa?

Anorexia nervosa is a life-threatening mental illness characterised by behaviours that interfere with maintaining an adequate weight.


While the causes of anorexia nervosa are not completely understood, most medical and psychological professionals acknowledge that an array of biological, social, genetic, and psychological factors play a role in increasing the risk of its onset.

Signs and symptoms of Anorexia Nervosa

The following are some common signs and symptoms. The presence of one or two, or even a few, signs or symptoms alone does not mean that someone has anorexia nervosa; however, they are deserving of concern. Especially when multiple signs and symptoms are present, investigating the possible causes promotes timely diagnosis and helps prevent severe health complications. 

  • Irritability, insomnia, and intense preoccupation with food, all of which can be directly related to insufficient nutrition
  • Weight loss (or a lack of appropriate weight gain in children)
  • Abdominal pain or non-specific gastrointestinal concerns
  • Dizziness and/or fainting
  • Feeling cold all the time
  • Anaemia
  • Social withdrawal
  • Feelings of inefficacy or hopelessness
  • Rigid, all-or-nothing thinking
  • Perfectionism
  • Dresses in layers or clothing that disguises one’s body shape even when not appropriate for the weather
  • Denies feeling hungry, or makes excuses to avoid meals

If you have concerns about restrictive eating patterns, this screening tool can help identify whether these patterns indicate the possible presence of anorexia nervosa. Note: this is not a diagnostic tool and not a substitute for a professional evaluation. 

Screen for Disordered Eating

Diagnosis criteria for Anorexia Nervosa

Anorexia nervosa typically begins around puberty, but can occur at any age. It is a life threatening mental illness characterized by, over a period of at least three months:

  1. Persistent behaviours that interfere with maintaining an adequate weight for health. These behaviours may include: restricting food, compensating for food intake through intense exercise, and/or purging through self-induced vomiting or misuse of medications like laxatives, diuretics, enemas, or insulin. 
    Anorexia nervosa was previously associated specifically with weight loss, making it difficult to recognize in children and adolescents. Children and adolescents need to gain weight in order to support healthy growth and development, so failing to gain weight or grow is just as concerning as weight loss;

  2. A powerful fear of gaining weight or becoming fat. The individual may feel this way even if they are maintaining a weight that is too low for their health. Their fear may translate into the use of a variety of techniques to evaluate their body size or weight – behaviours known as body checking. These techniques can include frequent weighing, obsessive measuring of body parts and the persistent use of mirrors to check for “fat.” It is important to note that weight loss or a lack of weight gain rarely calms body anxieties;

  3. Disturbance in how the person experiences their weight and shape. The person overestimates their body size, usually evaluates it negatively, and may feel their weight and shape matter more than most anything else about them; and

  4. The person does not fully appreciate the seriousness of their condition. Anorexia is linked with cardiac arrest, suicidality, and other causes of death.


Anorexia nervosa was previously associated with the loss of menstrual periods which made it difficult or impossible to identify in prepubescent youth or individuals who do not menstruate – this aspect is no longer necessary for diagnosis. 

Atypical anorexia nervosa shares the same characteristics as anorexia nervosa; however, the person’s weight is within or above the “average” range for age and height. This could occur, for instance, when a person starts at a higher weight and drops weight to the point that they are experiencing cardiac instability.

Common Co-Occurring Illnesses

The individual experiencing an eating disorder may also be affected by other mental illnesses, including: 

  • Depression or depressed mood
  • Anxiety (including generalized or social anxiety)
  • Obsessive-compulsive disorder
  • History of trauma or post-traumatic stress disorder

Anorexia nervosa may also be associated with self-harm and suicidality.

Anorexia Nervosa

Anorexia nervosa is a mental illness characterised by behaviours that interfere with maintaining an adequate weight. 

Biological, social, genetic, and psychological factors play a role in increasing the risk of its onset.

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Bulimia Nervosa

Bulimia nervosa is a mental illness characterised by periods of food restriction followed by binge eating, with recurrent compensating behaviours to “purge” the body of the food.

Biological, social, genetic, and psychological factors play a role in increasing the risk of its onset.

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Avoidant and Restrictive Food Intake Disorder

Avoidant/restrictive food intake disorder (ARFID) involves limitations in the amount and/or types of food consumed, but unlike anorexia, ARFID does not involve any distress about body shape or size, or fears of fatness. 

ARFID is a mental illness which can severely compromise growth, development, and health. 

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Binge Eating Disorder

Binge eating disorder is a mental illness that can seriously affect psychological and physical health. It is characterized by recurrent episodes of eating large quantities of food then experiencing shame, distress or guilt afterwards.

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Other Specified Feeding or Eating Disorder

Other Specified Feeding and Eating Disorders refers to atypical presentations of anorexia nervosa, bulimia nervosa, and binge eating disorder, among other eating disorders. 

These eating disorders are equally serious and as potentially life-threatening as the more typical presentations. 

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Other Eating Disorders

Including pica, rumination disorder and unspecified feeding or eating disorder

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