Researchers in Sweden, the United States, Australia, New Zealand, and Denmark are collecting health information and blood samples from people with anorexia nervosa or who have suffered from it at some point in their life and those without an eating disorder.
One of the researchers Cynthia Bulik, a clinical psychologist at Stockholm's Karolinska Institute, says anorexia nervosa affects about 1 percent of the population and for a long time scientists and doctors believed it was caused by societal or cultural factors, like people being told their were too fat or eating too many calories.
But, Bulik says, research shows that genetics play a more central role when it comes to those who are at risk for developing eating disorders.
"One of the things that I say commonly is that genes load the gun and environment pulls the trigger," she tells Swedish Television. "We know that anorexia nervosa is actually about 50 percent heritable"
So far, researchers in Sweden have gathered some 2,500 blood samples for the study and are encouraging more to take part in the Anorexia Nervosa Genetics Initiative, or Angi for short.
Bulik says if the investigation can crack the genetic code behind anorexia, it may make preventing and treating the illness easier.
"Right now we have no medications that are effective in treating the illness and that's because we don't understand the biology," she says.