Are eating disorders genetic? Here's the data

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Are eating disorders genetic? Here’s the data

Despite widespread misconceptions, eating disorders aren’t a choice, they’re serious, potentially life-threatening conditions. While social and environmental factors do influence someone’s risk of developing an eating disorder, decades of research have shown that biology, particularly family history, significantly increases someone’s risk for these conditions.

Groundbreaking studies from the late 1990s and early 2000s found that anorexia nervosa and bulimia nervosa (two of the most commonly diagnosed eating disorders) are strongly familial. For instance, one large study of nearly 2,000 people found that anorexia was rare among families without eating disorders, but female relatives of people with an eating disorder were more than 11 times as likely to develop anorexia themselves. Female relatives of individuals with bulimia had about four times the risk of developing the disorder, the study concluded.

More recent research has confirmed what these earlier findings suggested: Genetics play a significant role in eating disorders. A 2006 twin study in Sweden estimated that heritability accounts for 56% of the risk for anorexia nervosa. By contrast, environmental risk factors play a smaller role, according to the study.

But research has also revealed a major gap: Many studies have focused narrowly on white, thin, young women. Experts emphasize that these oversights shape who gets treated and who gets left behind, leading to underdiagnosis and undertreatment among men, people of color, older adults, and those with larger bodies. Excluding diverse populations only reinforces stereotypes about who is at risk, experts say, calling for more inclusive studies in order to better understand the full scope of eating disorders.

To better understand the role of biology in eating disorders, Charlie Health examined the existing research on genetics and family history as risk factors for the conditions.

Genetics can increase the risk of developing both anorexia and bulimia

Twin studies have concluded that there are shared genetic factors between anorexia nervosa and bulimia nervosa, meaning that having one disorder increases the likelihood of developing the other because of these shared underlying causes.

One 2019 twin study concluded that both anorexia and bulimia have similar heritability, about 43% for anorexia and 41% for bulimia. In other words, over 40% of the risk for developing anorexia or bulimia can be attributed to genetic factors passed down through families. The study also found that there is a strong genetic overlap between the two disorders, with a genetic correlation of 0.66 (which is quite high, according to researchers). So, the study provides solid evidence that the two disorders share a substantial portion of their genetic risk.

Binge eating disorder is also shown to be “moderately heritable”

There has been less research on binge eating disorder heritability than anorexia or bulimia, in part because it was more recently considered a formal eating disorder diagnosis. However, a 2010 study of female twins found that binge eating disorder is “moderately heritable,” with about 45% of the risk explained by genetic factors. By contrast, the shared environment contributed 13% to the risk, making genetics a greater risk factor than the environment. Also, individual binge eating disorder symptoms showed similar patterns, with genetics accounting for up to 43% of the variation, according to the study.

Avoidant restrictive food intake disorder (ARFID) is considered “highly heritable”

As mentioned, anorexia is the most studied eating disorder, but recent data from a Swedish twin study found that ARFID is “highly heritable.” According to the study, genetics explain about 79% of the risk. Unique environmental factors explained the remaining 21%. This means ARFID’s genetic influence is similar to other eating disorders and neurodevelopmental disorders, researchers concluded.

Specific genes may account for nearly one-fifth of the risk of developing anorexia

Recent genetic research, made possible by advanced sequencing and global data sharing, has begun to uncover the biological roots of eating disorders, especially anorexia. Genome-wide studies have identified multiple genetic risk regions, with common genetic variants accounting for up to 17% of the heritability of anorexia. This means that nearly one-fifth of the risk for developing anorexia can be traced to specific, inherited genetic factors. Also, some genes associated with lower body mass index (BMI) may directly increase the risk of developing anorexia, according to the study.

Interestingly, researchers found that anorexia shares a strong genetic connection with obsessive-compulsive disorder and metabolic traits, indicating that both psychological and biological factors contribute to the disorder.

The genetic risks of severe eating disorders remain less understood

One group of people often left out of genetic eating disorder studies is those with the most severe symptoms. A 2015 review found that people with severe and long-lasting anorexia nervosa—defined by at least 7 years of illness, failure to respond to treatment, extremely low BMI, and major impacts on quality of life — are often left out of genetic studies. This gap may slow progress in identifying genetic risk factors and developing better treatments for those with the most serious forms of the disorder.

This story was produced by Charlie Health and reviewed and distributed by Stacker.