Scientists have identified genetic variations that may help explain why weight-loss injections such as Wegovy and Mounjaro are more effective for some patients than others. The study, published in Nature, analysed data from nearly 28,000 people taking glucagon-like peptide 1 (GLP1) receptor agonists.
Researchers from 23andMe found that a variant in the GLP1 receptor gene, rs10305420, was associated with slightly greater weight loss. Another variant, rs1800437, was linked to nausea and vomiting in those taking tirzepatide (Mounjaro) but did not affect weight loss outcomes.
The findings suggest that genetic differences contribute to the variability in response, but the overall impact was modest. Lead researchers noted that non-genetic factors such as sex, drug type, dose, and duration explained a larger proportion of the differences in weight loss.
Dr Marie Spreckley, an obesity expert at the University of Cambridge who was not involved in the study, said the research provided plausible evidence that genetics play a role. However, she emphasised that behavioural, clinical, and treatment-related factors remain the dominant drivers of outcomes.
She added: 'The effects are modest and the evidence is not yet sufficient to support using genetic information to guide treatment decisions in routine clinical practice.' The study marks a step toward understanding variability in GLP1 therapy, but further research is needed before personalised prescribing becomes reality.
