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What is acute anorexia?

Anorexia nervosa (AN) is a dangerous mental health disorder that impacts the way people feel about their weight, body image, and the food they eat. It commonly manifests as a severe limitation of food intake, making it not just the deadliest eating disorder but the deadliest mental health disorder when left untreated.1

Acute anorexia represents an even more extreme version of AN, with patients dropping to very low—and very dangerous—body weights and generally experiencing a number of serious health complications.

It's essential for someone struggling with acute anorexia to receive appropriate medical care, especially since other dangerous complications can occur once a patient starts eating again. However, treatments are available, and a full recovery from acute anorexia is possible.

 minutes read
Last updated on 
February 20, 2024
February 20, 2024
Acute anorexia
In this article

Acute anorexia vs. anorexia nervosa

Anorexia nervosa is one of the most well-studied eating disorders. It involves extreme restrictions around food intake, driven by an intense fear of gaining weight and distorted thoughts about one's body shape and weight.

Acute anorexia, sometimes also called severe anorexia or extreme anorexia, is not a separate condition but instead describes a particularly severe case of AN.

There's no official definition of severe anorexia nervosa, but most analyses use body mass index (BMI) or body weight as a guide to determine when someone reaches this level. Some common designations of acute anorexia are a BMI under 15 or patients who are less than 65% of their ideal body weight.2

Signs and symptoms of severe anorexia 

Extreme anorexia is a more severe presentation of AN, so many of the signs and symptoms are shared. Some common warning signs include:6

  • A preoccupation with food, eating, calories, nutrition, or dieting
  • A fixation on appearance, especially concerning body shape or weight, in themselves and others
  • Strange rituals around food or eating, i.e., not letting foods touch each other on the plate or eating foods in a specific order
  • Avoiding situations or events that involve food
  • Depression, anxiety, irritability, and/or mood swings
  • Frequently checking oneself in the mirror or avoiding mirrors
  • Complaining about being or feeling "fat"
  • Wearing loose or baggy clothes to hide the shape of one's body

Eventually, people with AN start struggling with several physical complications, as well, due to the malnutrition that develops with extreme food restriction. This can result in:6

  • Low blood pressure
  • Arrhythmia or irregular heartbeat
  • Dry or yellowish skin
  • Absence of menstruation
  • Extreme cold intolerance
  • Constipation
  • Soft, downy hair (lanugo) growing on the body and face
  • Dizziness or fainting

In cases of acute anorexia nervosa, these behaviors and physical concerns will likely be even more extreme due to the additional complications of a dangerously low body weight. Someone who has reached this point may also be less likely to admit they need help or more deeply involved in maintaining their disordered eating patterns.

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Complications of extreme anorexia

While severe anorexia has many of the same health impacts as AN, with the ability to affect nearly every organ, the resulting complications are often more severe or life-threatening in the case of extreme anorexia.

Heart complications
Gastrointestinal complications
Bone and muscle complications

Treatment for acute anorexia

Unfortunately, in many cases, extreme anorexia leads to life-threatening complications. Many patients at this stage of illness are admitted to inpatient hospitalization, the highest level of care for eating disorders, where they can receive 24-hour medical treatment and monitoring.

The main priority of inpatient hospitalization is helping a patient become medically stable again, which means addressing issues that impact vital signs and extreme states of mind, such as suicidality.

Refeeding syndrome

Patients with acute anorexia risk developing what is called refeeding syndrome if they try to start eating again suddenly. It is essential to begin eating again inside of a hospital setting because this process can be particularly sensitive, as it triggers changes in hormonal, metabolic, and electrolyte levels, which can become deadly.4 This is why it's especially important for patients with severe anorexia to receive appropriate medical care.

Once someone is medically stable and past the early refeeding stages, they can continue treatment at residential facilities or through a partial hospitalization program. These levels of care still emphasize the physical needs of a person in recovery from acute AN, but they also incorporate mental health treatment that's necessary for long-term recovery.

Remote treatment is available

The experts at Within Health understand the complexity of eating disorders, including severe anorexia. Within Health offers evidence-based treatment personalized to each individual's unique case. Call our team today to see how you can start on the road to recovery.

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Recovering from acute anorexia

Getting out of immediate danger is the primary goal of severe anorexia treatment, but the next step of the journey has longer-term outlooks.

Each person's road to recovery is different but typically includes a combination of psychotherapy and nutritional counseling. Some patients may also require medication, whether to treat aspects of their eating disorder or commonly co-occurring mental health conditions like anxiety and depression. And others may find help in additional forms of care, like eating disorder support groups.

Disclaimer about "overeating": Within Health hesitatingly uses the word "overeating" because it is the term currently associated with this condition in society, however, we believe it inherently overlooks the various psychological aspects of this condition which are often interconnected with internalized diet culture, and a restrictive mindset about food. For the remainder of this piece, we will therefore be putting "overeating" in quotations to recognize that the diagnosis itself pathologizes behavior that is potentially hardwired and adaptive to a restrictive mindset.

Disclaimer about weight loss drugs: Within does not endorse the use of any weight loss drug or behavior and seeks to provide education on the insidious nature of diet culture. We understand the complex nature of disordered eating and eating disorders and strongly encourage anyone engaging in these behaviors to reach out for help as soon as possible. No statement should be taken as healthcare advice. All healthcare decisions should be made with your individual healthcare provider.


  1. Auger, N., Potter, B. J., Ukah, U. V., Low, N., Israël, M., Steiger, H., Healy-Profitós, J., & Paradis, G. (2021). Anorexia nervosa and the long-term risk of mortality in women. World Psychiatry, 20(3), 448–449.
  2. Gibson, D., Waters, A., Cost, J., Mascolo, M., & Mehler, P. S. (2020). Extreme anorexia nervosa: medical findings, outcomes, and inferences from a retrospective cohort. Journal of Eating Disorders, 8, 25. 
  3. Cost, J., Krantz, M. J., & Mehler, P. S. (2020). Medical complications of anorexia nervosa. Cleveland Clinic Journal of Medicine, 87(6), 361–366. 
  4. Skowrońska, A., Sójta, K., & Strzelecki, D. (2019). Refeeding syndrome as treatment complication of anorexia nervosa. Psychiatria polska, 53(5), 1113–1123.
  5. Norris, M., Harrison, M., Isserlin, L., Robinson, A., Feder, S., Sampson, M. (2016). Gastrointestinal complications associated with anorexia nervosa: A systematic review. International Journal of Eating Disorders, 49(3), 216-237.
  6. Anorexia nervosa. (n.d.). Mayo Clinic. Accessed December 2023.
  7. Giovinazzo, S., Sukkar, S. G., Rosa, G. M., Zappi, A., Bezante, G. P., Balbi, M., & Brunelli, C. (2019). Anorexia nervosa and heart disease: a systematic review. Eating and Weight Disorders, 24(2), 199–207.
  8. Jáuregui-Garrido, B., & Jáuregui-Lobera, I. (2012). Sudden death in eating disorders. Vascular health and risk management, 8, 91–98.


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Further reading

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