GLP-1 receptor agonists such as semaglutide, tirzepatide, and their cousins have earned their reputation as one of medicine’s genuine breakthroughs. But the enthusiasm surrounding them has curdled into a dangerous assumption: that they are a universal fix for obesity and metabolic disease. The data say otherwise, and it’s time the public conversation caught up.
The Non-Responder Problem Is Real and Bigger Than Marketing Suggests
Clinical trials themselves show the cracks. Although most participants in clinical trials lose more than 10% of their body weight, about one in ten achieve less than 5% and are considered non-responders. In the landmark STEP 1 trial for semaglutide, approximately 13.6% of participants failed to achieve even a 5% reduction in total body weight, and in real-world settings, nonresponse rates may reach 20% to 25% when additional clinical variables are considered. A separate retrospective cohort of nearly 500 adults on semaglutide or liraglutide found 17.8% of this cohort did not respond in terms of weight loss to GLP-1 RA treatment.
Crucially, increasing medication doses does not consistently overcome this resistance, suggesting the barrier is biological rather than behavioral. This matters enormously, because non-response has too often been quietly blamed on the patient like insufficient willpower, poor adherence, “cheating” on diet. Yale bariatric surgery chief Dr. John Morton pushes back directly on that framing, noting that non-responders often have more advanced obesity, with a body mass index (BMI) above 40, a group that has been underrepresented in many GLP-1 studies, and that clinicians should avoid terms like “failure” since genetic, treatment-related, or environmental factors may be the cause of non-response.
The Biology Behind the Variation
A 2026 genetic study published in Nature helps explain why. Researchers found that genetic variants in GLP1R and GIPR, which encode targets of GLP-1-based medications, offer insights into why responses to these drugs vary and who might face adverse effects, and separately estimated that approximately 10% to 14% of patients may have genetically driven GLP-1 resistance. Sex is another variable: women tend to lose more weight on GLP-1 medications than men, with researchers speculating that estrogen may interact with appetite-regulation pathways, though this remains theoretical. Metabolic phenotype matters too, for instance, a 52-week prospective study found responders tended to have elevated BMI, waist circumference, hepatic steatosis indices, fat mass, and insulin levels at baseline, while female gender, younger age, shorter disease duration, and non-use of metformin prior to enrollment were significantly associated with response. A comprehensive review concluded plainly: no single baseline characteristic reliably predicts response.
Tolerability, Cost, and the Discontinuation Crisis
Even when GLP-1s work biologically, they often don’t work practically. Tolerability also differs substantially, with at least one in three users experiencing adverse events, such as nausea, vomiting, diarrhoea or constipation. The downstream effect is a startling dropout rate. A JAMA Network Open cohort study of over 125,000 adults found the discontinuation rate of GLP-1 medication was 53.6% at 1 year and 72.2% at 2 years, with adults with type 2 diabetes had lower discontinuation rates at 1 year (46.5% vs. 64.8%) and 2 years (64.1% vs. 84.4%) than those without type 2 diabetes. A separate meta-analysis of nearly 446,000 patients found nearly half (48.7%) of patients who begin GLP-1 RAs discontinue the medications within one year, driven by GI side effects, high costs, medication shortages, and perceived lack of benefit. A Danish population study similarly found that more than half of semaglutide users in Denmark discontinued within a year, and that users in low-income areas were 14% more likely to discontinue use within the first year compared with users in higher-income areas. This is not a fringe problem, it’s the modal patient experience, and it falls hardest on those with the least financial cushion.
What Are the Alternatives?
None of this makes GLP-1s bad medicine. It makes them one tool among several, not a monotherapy for a heterogeneous disease. The realistic alternatives fall into a few categories:
- Bariatric surgery remains the most durable option for severe obesity. Real-world data presented at the American Society for Metabolic and Bariatric Surgery found that patients who underwent sleeve gastrectomy or gastric bypass lost approximately five times more weight over two years than those taking GLP-1 medications. It carries surgical risk and requires lifelong lifestyle adherence, but for non-responders with severe obesity it is a proven, durable path, and it’s being used less, even as GLP-1 prescriptions surge more than 140% between 2022 and 2024, while bariatric surgeries declined by more than 34% during the same stretch.
- Older oral anti-obesity drugs still have a role. Phentermine-topiramate combinations produce roughly 8–12% weight loss, and naltrexone-bupropion tends to work best for reward-driven or emotional eating, with average weight loss around 5–9%, both inexpensive, oral, and useful for patients who can’t tolerate or afford injectables. Notably, phentermine added after a poor initial GLP-1 response has helped some patients lose more weight even after stopping the GLP-1 altogether.
- Sequencing and combination strategies using GLP-1s alongside bariatric surgery, or switching drug classes (e.g., from a GLP-1-only agent to a dual GLP-1/GIP agonist like tirzepatide) based on early response at 6 months, which strongly predicts longer-term outcomes.
- Structured behavioral and lifestyle programs, ideally paired with clinician support to manage side effects and set realistic expectations, which meaningfully improve persistence with any pharmacologic approach.
- Emerging genetically informed prescribing: while not yet ready for routine clinical use, pharmacogenomic research may eventually let physicians predict non-response before a patient endures months of side effects for minimal benefit.
The Bottom Line
Obesity is not one disease with one mechanism, and it was always unlikely that one drug class would work uniformly across a biologically diverse population. The honest, evidence-based message isn’t “GLP-1s are overhyped”, rather it’s that they are one powerful option in a toolkit that must include surgery, older pharmacotherapies, behavioral support, and eventually, genetically tailored prescribing. Patients deserve to hear that up front, rather than being quietly blamed for a stalled scale that their biology, not their willpower, put there.
Sources:
Grosicki, G. J., et al. (2025). Glucagon-like peptide-1 receptor agonists discontinuation is higher in individuals with overweight and obesity without type 2 diabetes. Diabetes, Obesity and Metabolism. https://pubmed.ncbi.nlm.nih.gov/39743934/
Harvard Health Publishing. (2026). GLP-1 drugs versus bariatric surgery for treating obesity. https://www.health.harvard.edu/weight-loss/glp-1-drugs-versus-bariatric-surgery-for-treating-obesity
