Anorexia nervosa is an eating disorder that can cause:

  • a distorted body image
  • an irrational fear of weight gain or being overweight
  • a fixation on controlling weight and body size

People with anorexia often use extreme measures to maintain or lose their weight. This includes restricting what they eat, vomiting, and exercising excessively.

The causes of anorexia nervosa are complex. For decades, doctors believed anorexia was a psychological illness. They chalked the eating disorder up to picky eating or attention-seeking behaviors.

Today, it’s clear anorexia nervosa is the result of a combination of genetic and environmental factors. The disorder appears to have a strong relationship to other psychiatric disorders, like anxiety and depression. People with a family history of anorexia are more likely to have it, too.

But genes and environment on their own aren’t enough to explain why some people develop anorexia. This article will explain the research that connects anorexia nervosa and a person’s genes. It will also look at what, if anything, you can do to prevent it.

Anorexia nervosa: Facts and figures

  • Anorexia nervosa affects 0.9 to 4 percent of women and 0.3 percent of men.
  • Female relatives of people with anorexia nervosa have an 11-fold greater risk of developing anorexia nervosa compared to people without that familial connection.
  • More than 50 percent of the risk of developing an eating disorder is due to genetic factors.
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In the last several decades, researchers have tried to understand the underlying causes of anorexia nervosa. While doctors once considered it a psychological condition, newer research has revealed that anorexia nervosa might have a significant genetic component.

Numerous studies have identified specific chromosomes and genes that may be part of the equation. One study found that variations in specific regions of chromosome 1 were common in people with anorexia. These chromosomal regions house several hundred genes that help to regulate:

  • appetite
  • depression
  • satiety (feeling “full”)
  • anxiety

This suggests that problems in signaling pathways in your brain may trigger anorexia. If specific genes are affected, for example, a person may feel hungry or seem to have an appetite, but they may be unable to eat when they make or get food.

Research has also found that these gene mutations run in families. These results come from several different types of studies.

First, family studies show that first-degree relatives of people with anorexia nervosa have 10 times the risk for the disorder than people without the family connection. A first-degree relative is a parent, sibling, or child. What’s more, your risk of developing any eating disorder is higher if you have a relative with anorexia.

Twin studies help researchers understand whether traits are due to genetics or environment. Monozygotic twins, or twins born from the same egg and sperm, have identical genes for the most part. Any variations in the genes would likely be the result of other factors.

One twin study found that monozygotic twins are more likely to share an anorexia diagnosis than twins born of separate eggs. While this doesn’t mean all twins will develop the eating disorder if their sibling does, it does point to the presence of genetic factors.

To help understand which genes may be responsible, genome-wide association studies (GWAS) have compared the genes of thousands of people with anorexia nervosa to the genes of those without. They’ve identified several genes that could be related to the condition.

GWAS studies have also been able to identify other conditions that commonly occur in people with those genetic variations. These conditions include:

There’s no one specific cause for anorexia nervosa. Instead, a complex interplay of genetics and environment appears to be at work.

Some researchers call anorexia a “metabo-psychiatric illness.” That means it has both metabolic and psychiatric causes.

The metabolic causes may be due to interruptions in the pathways that control several functions in the body. These pathways include:

  • Serotonin helps to regulate appetite, food intake, mood, and anxiety. If serotonin is not in balance, it may result in eating disorders, anxiety, or depression.
  • Dopamine helps to regulate emotions, motivation, and motor activity. If dopamine levels are irregular, it could cause food aversion, weight loss, and even menstrual dysfunction.
  • Vitamin D3 is connected to anorexia, obesity, and diabetes. It helps to regulate sex steroid hormone production and inflammation. People with low vitamin D3 levels are more likely to have fatigue, depression, and metabolic disorders.
  • Hormones like ghrelin and leptin help to regulate your appetite. An imbalance in these hormones can affect reward mechanisms in your brain and make food less desirable.
  • Cannabinoid receptors in your brain are responsible for feelings of satiety and satisfaction. If these receptors are blocked or interrupted, you may not feel energized or fulfilled by food intake. You may have a low appetite as a result.

Recent research has identified eight gene locations that might play a role in developing an eating disorder. This study looked at the genes of 16,992 people with anorexia nervosa and 55,525 without it.

Earlier research identified two specific genes that greatly increase a person’s risk of developing an eating disorder. These two genes, ESRRA and HDAC4, increase a person’s chance of developing an eating disorder by 90 and 85 percent, respectively.

These genes, as well as some of the others identified by researchers, are involved in signaling your brain’s appetite. Blockages or interruptions in the appetite pathways may impact how a person interprets hunger.

These same areas are also related to other health issues, such as anxiety and depression. It’s unclear what relationship these psychological conditions might have on developing anorexia or other eating disorders. Studies have linked some of these genes to the development of other metabolic conditions, including type 2 diabetes.

Still, researchers believe hundreds of genes in your chromosomes significantly affect eating disorder development. They’re just beginning to understand how these genes affect your risk for anorexia and other conditions.

Research has uncovered more than just possible relationships between your genes and your risk of developing an eating disorder. A 2020 review notes that anorexia nervosa is closely related to other syndromes and health conditions. These include:

  • sarcoidosis: an inflammatory skin condition that causes patches of red, swollen skin
  • argininemia: a deficiency of the enzyme arginase, which might result in vomiting and muscle stiffness
  • infantile hypophosphatasia: a developmental disorder that impacts the growth of bones and teeth and can cause weak, soft bones
  • cyclic vomiting syndrome: recurrent episodes of nausea and vomiting
  • distal renal tubular acidosis: a condition that occurs when the kidneys are unable to remove enough acid from the body, resulting in stunted or delayed growth and possibly anorexia

Risk factors for anorexia nervosa include:

  • having a close relative with an eating disorder or other mental health issue
  • previous diagnosis of anxiety, depression, or addiction
  • a history of dieting or other weight-control measures
  • psychological tendencies like perfectionism, body image dissatisfaction, and rigid behavior patterns
  • a history of weight-related stigmas, including bullying and teasing

It’s not yet clear if you can prevent anorexia nervosa. What might be promising, however, is that research is helping doctors understand who may be at greater risk for developing it.

For those at high risk, doctors and family members may monitor for symptoms of anorexia nervosa and consider early treatment to prevent worsening symptoms.

Symptoms of anorexia nervosa include:

  • changes in mood
  • changes in eating patterns
  • negative body image or critical comments about one’s body
  • extreme weight loss
  • denial of hunger
  • excessive or extreme exercise routines
  • alcohol or drug use and abuse

Resources for support

If you are concerned that you or a family member may have anorexia nervosa, early support and treatment may be able to help you. Make an appointment to see a doctor. They may be able to connect you with local mental health resources or organizations that specialize in treating eating disorders.

Additionally, these national organizations have many great resources:

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In recent years, researchers have come to understand that anorexia nervosa is the result of a complex set of causes. Environmental factors, such as exposure to diet culture and weight-targeted social behaviors, play a role. But a person’s genes also have a significant impact.

People who have family members with anorexia nervosa or other eating disorders are more likely to develop anorexia themselves. Having a first-degree family member with the disorder significantly increases your risk.

But there is good news. As we learn more about the role of genes in anorexia, doctors and researchers can work to develop potential treatment or prevention methods. Understanding this complex relationship may help make the condition easier to diagnose, treat, and perhaps even prevent.