Researchers identified six regions of the genome (parts of DNA) associated with binge-eating behaviour.
One of these regions is near a gene called FTO, well known for its relationship with body weight.
Additionally, eight different genomic regions were associated with anorexia nervosa.
Professor Martin Kennedy, from the Department of Pathology and Molecular Medicine, said the study provided some of the “clearest evidence yet” that psychiatric and metabolic biology played a role in the disorders.
“By analysing DNA from tens of thousands of people worldwide with binge eating or anorexia nervosa, we can start to see clear genetic signatures for each condition,” he said.
Genetic factors linked to a higher body weight were also associated with increased likelihood of binge eating.
For anorexia nervosa, the relationship was in the opposite direction, with genetic factors linked to higher body weight appearing to reduce the likelihood of developing the disorder.
Researchers found that the genetic contribution to eating disorders cannot simply be explained by genes influencing body weight or body mass index.
The findings instead support the concept of eating disorders as “metabo-psychiatric” conditions – illnesses shaped by an interplay of metabolic and psychiatric genetic factors.
Otago researchers contributed genetic data from more than 500 local participants. Photo / 123RF
Associate Professor Jenny Jordan, a clinical psychologist in the Department of Psychological Health, said the findings challenged the idea that eating disorders could be understood solely through a psychological lens.
“Even though these two conditions both fall under the category of eating disorders, they clearly differ deeply on a biological level,” Jordan said.
Jordan said this represented an important shift in understanding and potentially treating eating disorders.
“These results not only help us understand both shared and distinct causes of these eating-related traits but may also help us develop more precise treatments targeting the specific biology of each condition,” she said.
The researchers also found genetic connections between both conditions and other psychiatric disorders, including depression and anxiety.
However, the patterns differed, with anorexia nervosa displaying a stronger genetic relationship with obsessive-compulsive disorder, and binge eating more strongly associated with ADHD.
The next phase of the research will draw on about 4000 New Zealand participants who have contributed to the Eating Disorder Genetics Initiative (EDGI), further strengthening New Zealand’s contribution to international eating disorder research.
Jordan said expanding the research would be important for understanding the full spectrum of eating disorders and could help develop more targeted approaches to treatment and prevention.