New genetic clues point beyond body weight in eating disorders

Clinical Takeaway: Don’t let body size drive assumptions about eating-disorder biology or risk. Binge-eating symptoms warrant attention across the weight spectrum, along with psychiatric and impulse-control comorbidities.

Eating disorders are clinically distinct but often overlap in symptoms and may change presentation over time. Although body weight is central to the diagnosis of anorexia nervosa and is often associated with binge-eating disorders, prior genetic research has focused heavily on anorexia and has left the biology of binge eating comparatively understudied.

An international genomic meta-analysis compared 39,279 people with broadly defined binge-eating behavior with more than 1.2 million controls and separately analyzed 24,223 people with anorexia nervosa. Researchers identified 6 genomic loci associated with binge eating and 8 with anorexia nervosa; 2 of the anorexia loci had not been identified previously.

Despite their clinical differences, binge eating and anorexia showed moderate genetic overlap and broadly similar positive genetic correlations with several psychiatric conditions, including major depression, bipolar disorder, anxiety, autism, and schizophrenia. Binge eating, however, showed stronger links with ADHD and with behaviors related to impulsivity, including smoking, problematic alcohol use, and general risk tolerance.

The sharpest contrast involved body composition. Genetic liability to binge eating was positively correlated with BMI, body fat, fat mass, and waist-to-hip ratio, while anorexia showed correlations in the opposite direction. Yet BMI-related genetics accounted for only about 12% of genetic variance in binge eating and 10% in anorexia—meaning roughly 88% to 90% of the genetic signal was independent of BMI.

A binge-eating locus near FTO, a gene long associated with higher body weight, also suggests binge eating may help explain part of FTO’s relationship with BMI.

“This research confirms on a genetic level that eating disorders are not just about body weight,” said study co-author Helena Davies, PhD.

The authors caution that the analyses primarily included people of European ancestry and predominantly female participants, and current polygenic scores remain too weak for clinical prediction.

Source: Termorshuizen JD, et al. (2026 Aug 19) Nat Ment Health. Genomic meta-analyses of binge-eating behavior and anorexia nervosa yield insights into the unique and shared biology of eating disorder phenotypes