Biting deep

Genes play a significant role in whether people develop an eating disorder.

- Nicky Pellegrino

Eating disorders were previously thought to be caused by sociocultural factors but in the past couple of decades, science has been busting that and other myths. Studies with twins were the first to show there is a significant genetic influence, and now researchers are working to identify exactly which genes affect a person's chance of developing disordered eating.

Cynthia Bulik is at the forefront of this work. The professor of eating disorders at the University of North Carolina leads research teams both there and in Sweden. Her work is reshaping how we think about this illness.

For instance, in 2018, the Anorexia Nervosa Genetics Initiative (ANGI) found an overlap with psychiatric conditions such as obsessive-compulsive disorder, depression, anxiety and schizophrenia. Perhaps more unexpectedly, it also identified that some of the same genes that raised the risk of developing type 2 diabetes actually lowered the risk of anorexia nervosa.

"The big take-home message from that study was that this isn't only psychiatric; it's metabolic," says Bulik.

ANGI was philanthropically funded and narrow in its focus. Bulik is now working on a follow-up study, the Eating Disorders Genetic Initiative (EDGI), that will include 3500 New Zealanders and tell us a lot more about conditions estimated to affect 9% of the world's population, or 700 million people.

Anorexia is the most visible of the eating disorders as people starve themselves and over-exercise until they are very gaunt. It is also considered the most deadly and severe. However, binge-eating disorder is three times as common and more people also have bulimia nervosa the condition that Diana, Princess of Wales, suffered from, where people eat large amounts of food then purge to get rid of the surplus calories. Both can damage health.