Major international study marks step forward in genetic understanding of eating disorders

New research led by the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London, in collaboration with an international partnership of researchers, has, for the first time, compared the genetics of people with binge eating versus those without any eating disorder. The paper also includes the largest ever genetic study of anorexia nervosa.

The research, published in Nature Mental Health found that genetic associations with binge eating and with anorexia nervosa were not the same as those with body mass index, despite body mass index being an important factor in both conditions.

Dr Helena Davies, postdoctoral research fellow at the IoPPN and joint-first author on the study, said: “This research confirms on a genetic level that eating disorders are not just about body weight; many of the versions of genes linked to these conditions are different from the versions of genes that are linked to how much someone weighs.”

Researchers identified six areas in the genome, also known as loci, associated with binge eating and eight loci associated with anorexia nervosa in people from European backgrounds.

Binge eating is a symptom that can occur across different eating disorders, most notably binge-eating disorder, but also bulimia nervosa, some cases of anorexia nervosa, and other eating disorders. In this study, the researchers analysed the genetics of the symptom of binge eating, rather than examining specific diagnoses like binge-eating disorder that include binge eating alongside other symptoms.

The researchers compared the DNA of people with binge eating to that of people without this symptom, utilising 27 global datasets and encompassing almost 40,000 individuals with binge eating and over 1.2 million unaffected people. They also compared the DNA of about 25,000 people with anorexia nervosa with the same unaffected individuals.

An analysis of the data revealed six loci associated with binge eating and eight loci associated with anorexia in people from European backgrounds. Six of the anorexia nervosa loci had been implicated in a 2019 genetic study of anorexia, further strengthening the evidence that they play a role in the condition. It is the first time two of the loci associated with anorexia had been identified.

Dr Jonathan Coleman, Senior Lecturer in Statistical Genetics at King’s IoPPN and lead senior author on the study, said, “We’ve been making important progress in understanding the genetics of anorexia nervosa for several years, but that’s only one of several eating disorders that have major impacts on people’s lives. This work is really important – we go beyond anorexia nervosa and start to understand the genetics of binge eating, which affects many people with eating disorders. We’re hopeful that our findings will allow future research to improve the lives of people with all eating disorders.”

Some of the binge-eating loci have previously been linked to body size traits, including one near a well-known gene called FTO. FTO has been studied for years because it is tied to higher body weight, and these new results suggest that binge eating may help explain part of the connection between FTO and higher BMI.

The researchers now plan to expand analyses to include other eating disorders such as atypical presentations and Avoidant/Restrictive Food Intake Disorder (ARFID), as well as global ancestries, in order to maximise discovery and improve the relevance of findings across populations, ultimately ensuring that genetic insights benefit people worldwide.

The study was an output of the Eating Disorders Working Group of the Psychiatric Genomics Consortium, which is a group of scientists that focus on meta- and mega-analyses of psychiatric eating disorder and symptom genetic studies. This phase of work by the Consortium was partially funded by the US National Institute for Health (NIH). The researchers were supported by a range of bodies including the National Institute for Health and Care Research (NIHR) Biomedical Research Centre: Maudsley.