1 in 10 People May Be Resistant to GLP-1 Drugs — What the Science Says
If you've started a GLP-1 and aren't seeing the weight loss that clinical trials promise, you might not be doing anything wrong. Emerging research suggests genetics plays a meaningful role in how well these medications work — and roughly 10% of the population may carry variants that reduce their effectiveness.
The Stanford Discovery: PAM Gene Variants
A study published in Genome Medicine on April 10, 2026 — the result of a decade-long international collaboration — found that variants in a gene called PAM are carried by roughly 10% of the general population and appear to cause what researchers are calling "GLP-1 resistance."
People with these PAM variants have higher circulating levels of GLP-1 in their blood, but the hormone appears to be less biologically effective. The researchers found that in clinical trials of GLP-1 receptor agonists for diabetes, individuals with these variants showed reduced ability to lower blood glucose levels after six months of treatment.
The mechanism is still being worked out. The PAM gene is involved in a chemical modification process that appears necessary for GLP-1 to function properly. Without it, the hormone is present but less active — like having a key that fits the lock but doesn't turn smoothly.
The 23andMe Finding: GLP1R and GIPR Variants
A separate study published in Nature on April 8, 2026 took a different approach. Researchers at 23andMe conducted a genome-wide association study of 27,885 people who had taken GLP-1 receptor agonists, analyzing self-reported weight loss and side effects.
They identified a missense variant in the GLP1R gene (the gene that encodes the GLP-1 receptor itself) that was significantly associated with increased medication effectiveness — roughly an additional 0.76 kg (1.7 pounds) of weight loss per copy of the beneficial allele.
They also found that variants in GIPR — the receptor for a related hormone called GIP — predicted nausea and vomiting in patients taking tirzepatide (which activates both GLP-1 and GIP receptors), but not in patients taking semaglutide (which activates only GLP-1 receptors).
What This Means for You
If you're a strong responder: You may carry favorable GLP1R variants. Keep doing what you're doing.
If you're a poor responder: This isn't a willpower issue. Genetics may be a factor. Options to discuss with your provider include dose adjustment, switching between semaglutide and tirzepatide (since they work through partially different mechanisms), or adding lifestyle interventions that target different pathways.
Should you get genetic testing? 23andMe is already offering GLP-1 response information through its Total Health platform. However, most clinical experts say the genetic findings aren't yet actionable enough to guide treatment decisions. The field is moving fast — this will likely change within the next 1-2 years.
The Bigger Picture: Precision Obesity Medicine
The 23andMe study also revealed differential effectiveness by ancestry, with GLP-1 medications showing the strongest effects in people of European ancestry, lower effects in Latino populations, and the least effectiveness in African American populations. People with Type 2 diabetes also showed about 2.87 percentage points less BMI reduction on average.
These findings point toward a future where GLP-1 prescribing isn't one-size-fits-all. The right medication, the right dose, and the right expectations may eventually be informed by your individual genetics.
Get Started with a GLP-1 Program
Regardless of genetics, GLP-1 medications produce clinically meaningful weight loss for the vast majority of patients. If you haven't tried one yet, don't let the 10% resistance statistic deter you — 90% of people don't carry these variants.