Can Eating Disorders Be Genetic?

Anorexia may be characterized by a lack of consumption, but the disease is all-consuming. Enduring the disorder at age 14 and again at 17, my every moment was preoccupied with stress and anxiety surrounding food and my wasting body, coupled with an overwhelming and deep, implacable pain. Within months, my will to live was as faint as my skeletal form.

Eating disorders affect at least 9 percent of people worldwide, according to the National Association of Anorexia Nervosa and Associated Eating Disorders (ANAD) and are the second-deadliest mental illness, next to opioid use disorder, causing about 10,200 deaths per year.

These disorders, the most prevalent of which include anorexia, bulimia, binge eating disorder (BED) and other specified eating disorders (OSFED), can pervade all facets of a person's life and well-being, from their emotional to sexual health.

They are highly treatable, and treatment can typically restore sexual well-being and fertility along with overall health. However, many people have trouble finding support or achieving long-term recovery, in part because the conditions and their origins are not fully understood.

Doctors typically consider eating disorders as psychological ailments heavily influenced by environmental and sociocultural factors. But recent research suggested genetics contribute as much—if not more—to their development.

"Eating disorders are complex psychiatric conditions and various factors contribute to both the onset of the disorder and maintenance of its symptoms," said Samantha DeCaro, Psy.D., a Philadelphia-based therapist and director of clinical outreach and education for The Renfrew Center. "Research suggests that the onset of an eating disorder seems to occur due to a complex interaction between genetics and environment. The presence of sociocultural, biological, psychological and developmental factors can all contribute to the level of risk for someone who is genetically vulnerable."

How eating disorders affect sexual health

Research indicates people with an eating disorder frequently experience low libido and high degrees of shame, body dissatisfaction and sexual anxiety.

Conditions such as depression and anxiety, which often co-occur, can exacerbate sexual challenges and contribute to difficulties such as erectile dysfunction (ED), lack of desire and lower levels of sexual satisfaction.

Malnutrition and high degrees of stress related to eating disorders can inhibit sex hormone production and fertility. Eating disorders may contribute to ED due to problems such as circulation difficulties and low testosterone, or cause irregular or absent periods and disrupted ovulation.

If an eating disorder isn't managed before pregnancy, persistent malnutrition can substantially affect pregnancy outcomes and a fetus' growth and development, contributing to problems such as pre-eclampsia, hemorrhage, low birth weight and developmental delays.

Generally, treatment for eating disorders—which involves a multidisciplinary approach—can rectify sexual health and fertility issues.

Experts hope developing more perspective on the conditions' causes—including genetic factors—can cultivate more effective treatments. Understanding the complex interplay of genetics, psychology, environment and other elements could even help to preempt eating disorders in genetically susceptible people.

More on Living and Dating with Eating Disorders

• You, Me and My Eating Disorder: A person’s relationship with their eating disorder can take precedence over romance, but partners can play a key part in recovery.
• How Eating Disorders Affect Your Sex Life: Besides problems like irregular periods and erectile dysfunction, people with EDs may struggle with intimacy or engage in risky, self-destructive sexual behaviors.
• Coming Clean and Telling Your Story: As terrifying as it may be, it’s best to be honest with your partner about your eating disorder. Doing so may even improve your relationship.

What does the research say about eating disorders and genetics?

In her research, Cynthia Bulik, Ph.D., founding director of the Center of Excellence for Eating Disorders at the University of North Carolina School of Medicine in Chapel Hill, has found about 40-60 percent of a person's vulnerability to eating disorders may be attributable to genetics. Bulik is leading the Eating Disorders Genetics Initiative (EDGI), an international study funded by the National Institute of Mental Health (NIMH).

Bulik was involved in the first study to identify genetic variations, which may influence a person's likelihood of developing an eating disorder. Published in 2002 in the American Journal of Human Genetics, the groundbreaking study revealed people with anorexia tend to have variations in a region of chromosome 1, which contains hundreds of genes involved in neural signaling processes that influence mood, appetite, satiety and anxiety.

Researchers found genetic variations that lead to problems in neural pathways can increase the risk of developing an eating disorder. These findings have been the basis for several follow-up studies that appear to confirm the results.

Although the study focused on anorexia, experts say genetic variations could influence the development of all eating disorders, including bulimia, binge eating disorder—the most common specific eating disorder in the United States—and OSFED, an umbrella category for atypical manifestations of disordered eating.

That study, and several before and after, found people with a family history of eating disorders or disordered eating tend to be more vulnerable. In a 2019 study published in Psychiatric Clinics of North America, Bulik and her colleagues reported that people with a first-degree relative with anorexia are about 11 times more likely to develop it than people whose families do not have a history of anorexia.

Furthermore, researchers suggested the risk of developing any eating disorder was higher in people with a parent, sibling or child with anorexia.

Bulik said she became interested in the familial patterns of eating transmission in 1988. In her clinical work, she said she observed many patients with eating disorders had family members with depression, substance use disorders and eating disorders or disordered eating.

"This was a long time ago, so many people in the older generations were never detected or diagnosed with eating disorders," she said.

She began investigating more systematically, using twin designs to parse out what traits were attributable to genetics or environmental factors. Because monozygotic twins' genes are almost identical, genetic variations between them typically result from other elements.

In a study published in Biological Psychiatry, Bulik and colleagues found monozygotic or "identical" twins are more likely than "fraternal" twins—those born from separate eggs—to develop anorexia if their sibling does. Not all twins whose sibling has disordered eating will develop it themselves, but these results suggest genetics can affect likelihood.

"The twin studies confirmed that eating disorders run in families (are heritable) and that the familial pattern was primarily due to genetic factors," Bulik said. "But those studies can't pinpoint actual genes that influence risk. That is what led us to use molecular genetic approaches to begin to unpack which genes or genetic pathways influence risk for eating disorders."

Such approaches include genome-wide association studies (GWAS), which compare the genes of thousands of people with eating disorders to those without such conditions. One GWAS from 2013 identified two genes, ESRRA and HDAC4, which increase a person's likelihood of developing an eating disorder by 90 and 85 percent, respectively.

These—and other genes that researchers have implicated—play a part in neurological processes, which influence appetite. Bulik and other experts believe hundreds more genes likely contribute to eating disorder vulnerability.

GWAS studies have also reinforced other research indicating conditions that commonly co-occur with eating disorders, such as depression, anxiety, obsessive-compulsive disorder (OCD), autism, schizophrenia and attention-deficit/hyperactivity disorder (ADHD).

"Eating disorders are highly complex illnesses," said Harry A. Brandt, M.D., a Maryland-based psychiatrist and regional medical director at Eating Recovery Center. "We have learned through generations of genetic research that there are multiple genes that likely interact to create vulnerability to eating disorders. A majority of the genetic work to date has focused on anorexia nervosa, and we are now seeing an emerging focus on the entire range of eating disorders, including bulimia nervosa, binge eating disorder and avoidant restrictive food intake disorder."

He added that genetic researchers around the world are currently working together to collect data from large enough populations with eating disorders to unlock important associations between genetic variants and various eating disorders.

"This will help in our understanding of the biological pathways involved in susceptibility to illness, as well as the development of new treatments,” he said. “The explosion in genetic research with the development of new techniques is remarkably exciting."