While anorexia does not directly cause hair loss in itself, it frequently can cause a person to adjust their daily habits in such a way that it causes hair loss.
Hair loss is one of several physiological consequences of starvation.  Anorexia nervosa is characterized by an intense fear of gaining weight, even if one is currently at or below a minimally normal weight (based on established medical standards) for their age, height, and gender. This fear of weight gain often leads people who have anorexia to starve themselves.
What Causes Hair Loss?
Researchers do not fully understand the exact effect of nutrition on hair health, but it’s at least established that deficiency in certain nutrients can have an impact. 
Important nutrients for hair health include:
- Vitamin B3
- Fatty acids
- Vitamin D
- Vitamin A
- Vitamin E
- Folic acid
- Amino acids and proteins
As a person changes their diet and reduces how much food they eat, it is possible for them to develop multiple deficiencies at once. When faced with malnutrition, the human body often works to prioritize essential mechanisms, like brain health, over less essential mechanisms, like hair health.
Malnutrition can slow hair growth and make what hair is present more brittle.
Does Hair Loss Signal Severe Anorexia?
Notably, hair loss and its links to vitamin and mineral intake is an area that still needs more research. The role of vitamins and minerals in hair loss is complex, and a person with anorexia could potentially experience hair loss unrelated to anorexia or of which anorexia only plays a part. 
A lack of vital nutrients can lead to hair loss.
With that said, a nutrient-poor diet can undeniably have an effect on a person’s hair health. People struggling with anorexia often have difficulties taking in their recommended levels of nutrients due to their severe anxieties around eating and weight gain.
Hair loss and an overall low level of hair health can indicate a person’s anorexia is at least severe enough that they are suffering from malnutrition. In broad terms, it may mean a person is “starving” in the sense that their nutritional intake is below what their body needs for basic maintenance and that their overall health, not just their hair health, is likely suffering as a result.
Is It Time to Seek Treatment for Anorexia?
Anorexia is a condition that can cause an immense amount of stress. A person who has anorexia may find themselves unable to eat enough to maintain their health due to fears of potential weight gain. They may be unable to conceptualize their bodies in a realistic, healthy way.
Anorexia is also a mental health condition that is very difficult for someone to overcome without professional help. Generally, patients must work with a mental health professional to achieve a healthier body image and make strong progress toward recovery.
If you believe you have anorexia or another eating disorder that is beginning to affect any aspect of your health, hair health or otherwise, it is a good idea to consider seeking help. Many eating disorders can cause a person to pursue unrealistic and outright impossible weight goals that can do serious harm to their bodies, even as their mental health also suffers.
Talking about your fears and anxieties with a professional can help you understand their root cause. You can begin to make fundamental changes to your habits and the way you perceive yourself that can truly improve your overall quality of life.
- Sidiropoulos, M. (2007). Anorexia nervosa: The physiological consequences of starvation and the need for primary prevention efforts. McGill Journal of Medicine, 10(1), 20-5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2323541/.
- Guo, E.L., Katta, R. (2017). Diet and hair loss: effects of nutrient deficiency and supplement use. Dermatology Practical & Conceptual, 7(1), 1-10.
- Almohanna, H.M., Ahmed, A.A., Tsatalis, J.P., Tosti, A. (2019). The Role of Vitamins and Minerals in Hair Loss: A Review. Dermatology and Therapy, 9(1), 51-70.