Genetics may shape GLP-1 weight-loss drug response

Scientists from 23andMe and a nonprofit medical research institute said on Wednesday, April 8, 2026, that inherited genetic differences may help explain why people respond differently to GLP1 weight-loss medicines. The team reported that certain gene variants were linked to both the amount of weight loss and the likelihood of side effects among patients using widely prescribed treatments such as semaglutide (Wegovy) and tirzepatide (Mounjaro). The findings were published in the journal Nature .

The researchers analyzed data from 27,885 patients who were using GLP1 drugs. They identified two genetic variants that appeared to track with specific outcomes. One variant in the GLP1 receptor, rs10305420, was associated with slightly increased weight loss.

A second variant, rs1800437, was linked to nausea and vomiting among tirzepatide users. The researchers described these associations as part of a broader effort to understand why some patients experience stronger benefits or more pronounced adverse effects than others when taking the same class of medication. The study focused on GLP1 medicines that are used widely in obesity treatment.

GLP1 drugs work by mimicking natural gut hormones involved in appetite regulation, insulin release, and digestion. By influencing these pathways, the medicines can reduce appetite and affect metabolic processes, which is why they have become central to many obesity treatment approaches. The study’s results add to ongoing research into how biological differences may shape outcomes for patients using these therapies.

At the same time, the researchers said the overall role of genetics in explaining different responses was modest. They reported that non-genetic factors accounted for a substantially larger share of the variation in treatment response. Those factors included sex, the specific drug used, dose, and how long a patient remained on treatment.

Experts said the work represents progress toward more personalized obesity care, but they cautioned that the current evidence is not strong enough to support clinical decisions based only on genetic information. In practical terms, the findings point to potential future tools for tailoring treatment, while underscoring that most of the observed differences in outcomes still appear to be driven by factors other than genetics.

The researchers’ conclusions leave open questions about how these genetic signals might be used alongside other patient characteristics in real-world care.