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Anorexia nervosa and brain fog: What is it?

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Last updated on 
October 27, 2022
In this article

What is brain fog? 

Brain fog is considered to be a temporary mild cognitive impairment and sometimes thought of as an exaggerated mental fatigue. (1) Brain fog can occur in people with anorexia nervosa (AN), an eating disorder, as well as among people without this condition. 

A few common symptoms of brain fog include:

  • reduced cognition
  • reduced concentration 
  • loss of short term memory
  • tasks that involve mental activity take longer
  • inability to multitask
  • difficulty forming thoughts/haziness in thoughts
  • slow thinking
  • loss of long-term memory

How does anorexia nervosa contribute to brain fog? 

There’s no doubt about it – anorexia nervosa affects the brain. Food provides glucose also known as blood sugar, which is the primary fuel of the brain. When you don’t get enough glucose, your brain shifts to survival mode. It begins conserving energy as much as it can so high level thinking is diverted into survival. Survival mode involves the emotional brain, and thus survival is more emotional thinking. Thus, in AN, such behavior is more emotional than rational thinking. And when rational thinking is attempted, brain fog can occur. 

You don’t have to be struggling with AN to feel the effects of brain fog. Prolonged periods between eating can cause your blood sugar to fall and then the emotional ups and downs of low blood sugar can occur. However, in individuals with anorexia nervosa, this survival mode and brain fog is more long term for individuals with anorexia nervosa.

This lack of energy affects the brain in other ways as well. When Italian neurologists examined the Magnetic Resonance Images (MRIs) of 21 patients with AN and compared them to 27 people without AN, they found big differences. The gray and white matter of the brains of those with anorexia nervosa had shrunk, especially in the cerebellum, hypothalamus, caudate nucleus, frontal lobes, parietal lobes, and temporal lobes. It is thought that the loss of tissue mass in the frontal, parietal, and temporal lobes are most connected with the brain fog that individuals with anorexia nervosa have. 

There were two additional findings in the study. Those who had the disorder the longest had more changes to the cerebellum than those that were recently diagnosed. The second one was that as body weight decreased, the hypothalamus shrunk as well. (2) When the hypothalamus shrinks, emotion regulation becomes more of a challenge. 

With AN, there is not just one or two different vitamins and minerals at risk of deficiency, but many. Since nutrients usually work together, if one of them goes into deficiency, it can affect others. For example, if magnesium levels are low, vitamin D, calcium and phosphorus also will eventually go low. 

The nutrients that are responsible for brain function, and their symptoms when deficient, include the following: (5)

  • Vitamin E: Impaired balance.
  • Niacin: Dementia, depression, apathy, fatigue, disorientation, memory loss.
  • Biotin: Hallucinations, depression, seizures.
  • Pantothenic acid: Fatigue, insomnia, listlessness.
  • Thiamin: Cognitive impairment, confused and apathetic state with profound memory disorder, severe amnesia.
  • Vitamin B6: Abnormal EEG tests of the brain, irritability, depression, confusion.
  • Vitamin B12: Memory loss, disorientation, dementia with or without mood changes, damage to the myelin sheath covering the cranial nerves, spinal nerves and peripheral nerves.
  • Vitamin C: Fatigue.
  • Iodine: Brain damage, mental retardation, decreased IQ levels.
  • Copper: Central nervous system demyelination, inflammation of the nerves.
  • Iron: Taste buds wither away (atrophy), cognitive changes.
  • Magnesium: Mood changes, anxiety, anger outbursts, tremor, loss of appetite, personality changes.
  • Molybdenum: Anxiety, panic attacks.
  • Zinc: Behavioral disturbances, impaired taste, low appetite, fatigue.
  • Selenium: More susceptible to stress.
  • Sodium: Disorientation, fainting, brain swelling, seizures, coma, brain damage.

Anorexia nervosa and your brain

The good news is that brain restoration was most pronounced during the first half of inpatient treatment for AN, according to University of Zurich researchers. (2) The patients studied had been diagnosed with severe anorexia nervosa and yet they recuperated. The doctors stated that weight restoration treatment should be started as early as possible to achieve better regeneration, and a goal of a healthy body weight gave patients sufficient time to recover on both a psychological and a brain level. 

Nutrition therapy plays a critical role in the treatment of AN and its medical complications. 

The use of natural flavonoids for brain fog is also something that should be considered with the primary goal of renoursing and weight restoration, if required. For example, the flavone luteolin has been found to act as an antioxidant, anti-inflammatory, brain protector, memory improver, and inhibits brain damage. (3) 

One luteolin formulation in olive fruit extract was found to improve the attention of children with autism who notoriously have brain fog, according to scientists at Tufts Medical School in Boston. (3)

For any medical concerns around brain fog or other side effects of anorexia nervosa, please reach out to your medical doctor. For treatment, Within Health is here to assist you in recovering from any eating disorder.

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. Ocon, A. J. (2013). Caught in the thickness of brain fog: Exploring the cognitive symptoms of chronic fatigue syndrome. Frontiers in Physiology, 4. https://doi.org/10.3389/fphys.2013.00063 
  2. Kaufmann, L.-K., Hänggi, J., Jäncke, L., Baur, V., Piccirelli, M., Kollias, S., Schnyder, U., Martin-Soelch, C., & Milos, G. (2020). Age influences structural brain restoration during weight gain therapy in anorexia nervosa. Translational Psychiatry, 10(1). https://doi.org/10.1038/s41398-020-0809-7 
  3. Theoharides, T. C., Stewart, J. M., Hatziagelaki, E., & Kolaitis, G. (2015). Brain "fog," inflammation and obesity: key aspects of neuropsychiatric disorders improved by luteolin. Frontiers in neuroscience, 9, 225. https://doi.org/10.3389/fnins.2015.00225
  4. Ocon A. J. (2013). Caught in the thickness of brain fog: exploring the cognitive symptoms of Chronic Fatigue Syndrome. Frontiers in physiology, 4, 63. https://doi.org/10.3389/fphys.2013.00063
  5. Minerals. Linus Pauling Institute. (2016, October 5). Retrieved April 29, 2022, from https://lpi.oregonstate.edu/mic/minerals


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