A landmark international study involving University of Otago research and hundreds of New Zealand participants has identified distinct genetic signatures for binge eating and anorexia nervosa, challenging the traditional view of eating disorders as primarily psychological illnesses.
Led by researchers at King’s College London and the University of North Carolina, the study is the first to map and directly compare the genetic profiles of binge eating and anorexia nervosa at a large scale.
Associate Professor Jenny Jordan
The research, published in the UK Journal Nature Mental Health, includes genetic data from more than 500 New Zealand participants contributed by a University of Otago Faculty of Medicine - Christchurch Ōtautahi research team.
It shows that while binge eating and anorexia nervosa share some genetic influences – particularly those associated with other psychiatric conditions – they also differ in important and sometimes striking ways.
Associate Professor Jenny Jordan, a clinical psychologist in the Department of Psychological Health, says the findings challenge the idea that eating disorders can 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,” she says.
Professor Martin Kennedy from the Department of Pathology and Molecular Medicine, says the study provides some of the clearest evidence yet that eating disorders are influenced by both psychiatric and metabolic biology.
“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 says.
For the first time, researchers identified six regions of the genome associated with binge-eating behaviour, including one close to FTO, a gene well known for its relationship with body weight.
Eight different genomic regions were associated with anorexia nervosa. 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.
Professor Martin Kennedy
Genetic factors associated with higher body weight were also associated with an increased likelihood of binge eating. For anorexia nervosa, the relationship was in the opposite direction, with genetic factors associated with higher body weight appearing to reduce the likelihood of developing the disorder.
Importantly, the 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.
For Associate Professor Jordan, this represents an important shift in how eating disorders are understood and potentially treated.
“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 explains.
Eating disorders affect people across a wide range of body sizes and can have serious physical and psychological consequences. Recognising their biological complexity could ultimately help researchers develop treatments that are better matched to the underlying biology of individual conditions.
Professor Kennedy says the New Zealand contribution is also helping build the evidence base for the next generation of research.
“This research is fleshing out the genetic and biological underpinnings of eating disorders and will create new opportunities for improved treatment and ideally prevention,” he says.
“We are excited that so many New Zealand participants have agreed to contribute to these important international studies.”
The next phase of the research will draw on approximately 4000 New Zealand participants who have contributed to the Eating Disorder Genetics Initiative (EDGI), further strengthening Aotearoa New Zealand’s contribution to international eating disorder research.
Jordan says expanding the research in this way will be important for understanding the full spectrum of eating disorders and could help develop more targeted approaches to treatment and prevention.
Publication details:
Genome-wide association study of binge-eating behaviour and anorexia nervosa. https://doi.org/10.1101/2025.01.31.25321397
Journal: Nature Mental Health