Genetic Risk Factor for Eating Disorders

Today, researchers know that eating disorders are generally rooted in genetic vulnerabilities that lie in wait until they're triggered by common life stresses—going away to school, turbulent relationships, a family breakup.

"The thinking about disordered eating has changed dramatically over the last five years," says Cynthia Bulik, PhD, director of the Eating Disorders Program at the University of North Carolina in Chapel Hill. "When I first got into the field over 20 years ago, there were two beliefs. One was that these were socio-cultural disorders caused by young girls wanting to look like models. The other was that dysfunctional families caused eating disorders. That's about as far from current theory as you could imagine."

Holding up size zero fashion models as role models certainly wasn't helpful. But the notion that models and families actually caused eating disorders was damaging. "In fact," Bulik says, these two ideas "held back research and led people to believe these were disorders of choice." A disservice was done by blaming families for causing eating disorders when, in fact, most families were trying to figure out how to help their child.

"Genetic research has revolutionized our thinking," says Dr. Bulik. "We recognize a strong biological component and we're at a point where we're starting to identify genes that influence risk. We now know that somewhere between 50 and 80 percent of a person's risk of an eating disorder is due to genetic factors."

The Risk Factors

Although researchers are just beginning to uncover the genes—or groups of genes—involved in eating disorders and how they influence feeding-related hormones like leptin, grehlin, and cholecystokinin (CCK), these researchers already know that several personality traits and behaviors that may be influenced by those genes are associated with both anorexia and bulimia. As a result, those traits and behaviors are generally regarded as a red flag that may indicate you're at risk.

Childhood anxiety and a tendency toward perfectionism are known to be more prevalent in those with eating disorders than in others, for example, as is obsessive-compulsive disorder (OCD), a condition marked by obsessive thoughts, a need for control, and sometimes repetitive actions like hand-washing.

Another risk factor specific to anorexia is an ironic reaction to limiting food intake. "When most people go on a diet and watch their food intake, they tend to become moody, anxious, and grumpy," says Dr. Bulik. "But when people predisposed to anorexia monitor their food intake, it makes them less anxious and a lot more content."

In a culture that worships body size, however, the biggest risk factor for an eating disorder is dieting. Geneticists have a saying, says Dr. Bulik. "Genes load the gun, but the environment pulls the trigger." It means that someone might be genetically predisposed to anorexia, she explains, "but if they never go on that first extreme diet, they'll never develop the disorder. For both anorexia and bulimia, the diet is step one."

Once on a diet, those with a predisposition toward anorexia will find that they enjoy limiting food intake and keep on restricting. Those with a predisposition toward bulimia will find that when they restrict their eating, they'll binge until their bodies scream "I can't take this anymore!" Then there's a good chance they'll purge.

The Eating Continuum

Researchers generally perceive eating disorders along a continuum that they divide into three distinct—and occasionally overlapping—conditions. Over a lifespan, people can move across the continuum from one disorder to another, to no disorder at all, then relapse and end up back where they started. Or they can move from having a full-blown disorder to having a partial disorder with only a few symptoms. The one thing someone with an eating disorder can count on is this: The faster you get help the more likely you are to beat the disorder.

—Article contributed by Cynthia Bulik, PhD, Chapel Hill, NC.