Text Link

Learn more about the results we get at Within

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse varius enim in eros elementum tristique. Duis cursus, mi quis viverra ornare, eros dolor interdum nulla, ut commodo diam libero vitae erat. Aenean faucibus nibh et justo cursus id rutrum lorem imperdiet. Nunc ut sem vitae risus tristique posuere.

Learn more about the results we get at Within

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Suspendisse varius enim in eros elementum tristique. Duis cursus, mi quis viverra ornare, eros dolor interdum nulla, ut commodo diam libero vitae erat. Aenean faucibus nibh et justo cursus id rutrum lorem imperdiet. Nunc ut sem vitae risus tristique posuere.

Anorexia and hypermetabolism

Anorexia nervosa (AN) is a mental health condition, but the eating disorder nearly always has an outsized impact on someone's physical health, including by contributing to the development of hypermetabolism.

This influence on someone's basal metabolic rate can be dangerous and lead to many health complications if left untreated. But it's possible to ease the effects of both hypermetabolism and anorexia nervosa through a healthy weight restoration process.

 minutes read
Last updated on 
July 7, 2023
December 21, 2023
Anorexia and hypermetabolism
In this article

What is hypermetabolism? 

Hypermetabolism is a condition describing an increase in the body's basal metabolic rate (BMR), or the amount of calories required to perform basic, life-sustaining functions when the body is at rest. In other words, the BMR represents the minimum number of calories the body burns simply by existing.

When someone reaches a point of hypermetabolism, their BMR increases and their body starts burning higher amounts of calories, including while at rest. This often leads to weight loss, even with increased energy intake. 

Causes of hypermetabolism

Hypermetabolism or hypermetabolic conditions can occur in many different scenarios, particularly when the body needs to produce more energy than normal to heal itself.

For example, if someone has suffered severe burns, multiple fractures, infection or sepsis, traumatic brain injury, or undergone surgery, their body will become hypermetabolic, increasing energy output in order to facilitate the healing process.1,2,3,4

It's also possible for hypermetabolism to develop from other causes, including hyperthyroidism, a condition in which the thyroid produces too many hormones, ultimately speeding up the body's internal processes and kicking metabolism into overdrive.7

Hypermetabolism symptoms

Hypermetabolism may be useful in short stints, such as helping someone produce enough energy to facilitate healing, but if it occurs long-term, it can become a serious medical condition.

Some studies have shown that the increase of catabolic activity—or the breakdown of food into more usable components like carbohydrates, protein, and fat—can increase insulin resistance. This, in turn, can result in higher blood sugar levels, which, in itself, can bring on a number of other health complications.8

Other symptoms of hypermetabolism include:5

  • Anemia
  • Elevated or irregular heart rate
  • Increased body temperature
  • Shortness of breath
  • Muscle weakness and fatigue
  • Heat sensitivity
  • Excessive sweating

Hypermetabolism and anorexia 

When it comes to anorexia nervosa, hypermetabolism isn't a symptom of the condition, but rather a potential complication of recovery.

The disordered eating patterns generally associated with AN often lead to starvation or severe malnutrition, causing the body to break down fat and muscle in order to supply energy to sustain life. This has its own effect on the metabolic rate, generally working to slow the process down as the body adjusts to receiving less energy.

For people with AN and other restrictive eating disorders, the danger of becoming hypermetabolic sets in during the nutritional rehabilitation phase.6 When the body is used to receiving so little, the reintroduction of even a small amount of outside energy can kick the metabolic rate into high gear, as the body eagerly works to break down and absorb these additional resources.

Some studies have shown that people who struggle with AN remain hypermetabolic well into recovery, requiring even more calories than normal to maintain weight restoration long-term.6 They may also continue to lose weight easily or have trouble with weight gain, as the body continues to adjust to new food intake levels.6

Hypermetabolism and eating disorder recovery

Indeed, the refeeding process is often considered one of the most dangerous parts of AN recovery, especially early on. Medical supervision during this stage is very important.

In extreme cases of prolonged starvation, the body becomes depleted of many nutrients, fats, and proteins. If food is reintroduced too quickly, the hypermetabolism set off by this change can lead to rapid and dangerous changes and chemical reactions, including potentially deadly electrolyte imbalances and cardiac arrhythmias.10

Scientists are generally split on the proper pace to reintroduce calories to someone's diet, and much of the process depends deeply on details of individual cases. But in every case, it's important to work with a team of professionals to help restore weight in a safe and healthy way.

Finding help for anorexia nervosa

If you or a loved one are struggling with anorexia nervosa or another eating disorder and have lost significant body weight, it's important to seek out the appropriate type of treatment and care.

Treatment is within reach

Call our team at Within Health to learn more about remote treatment for anorexia nervosa. Our multidisciplinary team can build treatment plans tailored to your individual needs, and help ensure you get the care you need, without having to leave home.

Anorexia nervosa is dangerous, but it doesn't have to be destiny. Help is always available, and recovery is always possible.

Call (866) 293-0041

Your primary care physician, therapist, psychiatrist, or another trusted medical professional can help, giving you an official diagnosis, pointing you in the direction of a successful treatment program, or otherwise helping you plan the next best steps.

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. Jeschke. M. G. (2016). Postburn Hypermetabolism: Past, Present, and Future. Journal of Burn Care & Research, 37(2), 86–96.
  2. Pravda, J. (2014). Metabolic theory of septic shock. World Journal of Critical Care Medicine, 3(2), 45–54.
  3. LiVolsi, V. A., & Baloch, Z. W. (2018). The Pathology of Hyperthyroidism. Frontiers in endocrinology, 9, 737.
  4. Foley, N., Marshall, S., Pikul, J., Salter, K., & Teasell, R. (2008). Hypermetabolism following moderate to severe traumatic acute brain injury: a systematic review. Journal of neurotrauma, 25(12), 1415–1431.
  5. Dev, R., Hui, D., Chisholm, G., Delgado-Guay, M., Dalal, S., Del Fabbro, E., & Bruera, E. (2015). Hypermetabolism and symptom burden in advanced cancer patients evaluated in a cachexia clinic. Journal of cachexia, sarcopenia and muscle, 6(1), 95–98.
  6. Marzola, E., Nasser, J. A., Hashim, S. A., Shih, P.-an B., & Kaye, W. H. (2013). Nutritional rehabilitation in anorexia nervosa: Review of the literature and implications for treatment. BMC Psychiatry, 13(1).  
  7. Mullur, R., Liu, Y. Y., & Brent, G. A. (2014). Thyroid hormone regulation of metabolism. Physiological Reviews, 94(2), 355–382.
  8. Hypermetabolism. (n.d.). Science Direct. Accessed June 2023. 
  9. Yu, X., Peng, Q., Luo, X., An, T., Guan, J., & Wang, Z. (2016). Effects of Starvation on Lipid Metabolism and Gluconeogenesis in Yak. Asian-Australasian Journal of Animal Sciences, 29(11), 1593–1600.
  10. Mehanna, H. M., Moledina, J., & Travis, J. (2008). Refeeding syndrome: what it is, and how to prevent and treat it. BMJ, 336(7659), 1495–1498.


Further reading

Men with Anorexia: Symptoms, signs and treatment help

Anorexia nervosa (AN) is a dangerous eating disorder that impacts all facets of mental, emotional, and...

Exercise bulimia vs. anorexia athletica

Many people know at least a little bit about eating disorders like anorexia nervosa (AN) and bulimia...

Do I have anorexia nervosa?

Anorexia nervosa (AN) is an eating disorder that may manifest differently in different people and can...

What is weight restoration?

Weight restoration refers to the process of returning to a healthier body weight after experiencing weight...

Does anorexia cause dehydration?

Anorexia nervosa (AN) is a serious and life-threatening mental health condition that commonly manifests as...

Does anorexia face swelling occur?

The severe nutritional deficiency seen in those with anorexia nervosa (AN) can lead to edema, which is a...

Signs and symptoms of starvation

Malnutrition is an unfortunate and potentially dangerous condition that impacts the ways the body is able...

Anorexia health risks and dangers

Anorexia nervosa (AN) is a serious eating disorder that can result in a variety of medical complications...

Anorexia's effect on your organs

Anorexia nervosa (AN) is a serious mental health disorder, but the condition nearly always manifests as a...

Why does anorexia bloating occur?

While not an official medical term, “anorexia bloating” can be used to describe bloating that occurs as a...

Anorexia and bruising: Signs, causes, and healing

Anorexia nervosa (AN) is a dangerous mental health condition, but it can also manifest in several physical...

What happens to hair growth when you have anorexia?

Anorexia nervosa (AN) is a severe mental health disorder, characterized by an extreme fear of gaining...

What are the effects of anorexia on teeth and oral health?

Anorexia nervosa (AN) may be a mental health disorder, but it can have a number of physical consequences...

Mental health and physical medical complications of anorexia nervosa

Anorexia nervosa (AN) is a dangerous eating disorder that affects all facets of someone's life, with the...

Yellow skin in anorexia nervosa: Jaundice symptoms

Anorexia nervosa (AN), bulimia nervosa (BN), and other eating disorders affect more than someone's mental...

Edema in anorexia recovery: causes, symptoms and treatment

Edema anorexia is common in patients with both subtypes of anorexia, with...

Refeeding syndrome and anorexia

Anorexia nervosa (AN) is a dangerous eating disorder that requires specialized care and treatment to overcome.

How does anorexia affect the brain?

Anorexia nervosa (AN) is a serious mental health condition most often associated with extreme food...

How does anorexia affect eyesight?

Eating disorders like anorexia nervosa (AN), binge eating disorder (BED), and bulimia nervosa (BN) may each...

Can anorexia cause heart problems?

Eating disorders like anorexia nervosa (AN) are mental health conditions, but they can result in a number...

How anorexia affects hands: cold, shaking, tingling and discolored fingernails

You may not realize that the eating disorder anorexia nervosa (AN) can affect every part of the human body...

Does anorexia cause parotid gland swelling?

Anorexia nervosa (AN) does cause parotid gland swelling, particularly if AN is...

The occurrence of anorexia and mood swings

Anorexia nervosa (AN) is a serious eating disorder that involves caloric restriction...

Does anorexia cause diabetes?

Anorexia nervosa (AN) is a common eating disorder that can seriously impact someone's mental, physical, and...

Can eating disorders cause anemia?

Anemia is a condition that occurs when there aren’t enough healthy red blood cells in the...

What causes lanugo hair in anorexia?

The disordered eating patterns involved with anorexia nervosa (AN) can impact nearly every function of the...

Anorexia nervosa and brain fog: What is it?

Anorexia nervosa (AN) is a serious mental health condition, which can manifest as any number of complications.

Anorexia nervosa ketoacidosis symptoms

Anorexia nervosa (AN) is a serious mental health condition, but it can have just as many detrimental effects..

Anorexia and your digestive system

Anorexia nervosa (AN) can definitely affect your digestive system. One of the most...

Anorexia and the kidneys

Those who struggle with anorexia nervosa (AN) and bulimia nervosa (BN) often develop...

Anorexia joint pain, muscle, bone and body aches

Anorexia nervosa (AN) is a serious eating disorder that affects both the...

Can anorexia cause IBS (irritable bowel syndrome)?

Research highlights the increased prevalence of irritable bowel syndrome (IBS) in those suffering from an....

Anorexia and hypermetabolism

Anorexia nervosa (AN) is a mental health condition, but the eating disorder nearly always has an outsized...

Anorexia and lower back pain

Individuals with anorexia nervosa (AN) live with an intense fear of gaining...

Anorexia and gastroparesis

Gastroparesis (literally meaning “stomach paralysis) is a condition that affects the movement and muscles...

Anorexia and cachexia

Cachexia is a very serious, complex condition that occurs with anorexia...

Anorexia and constipation

Constipation, or not being able to pass stool regularly or completely, is a fairly common condition that...

Further reading

No items found.