In May 2026, Eli Lilly announced Phase 3 trial results for retatrutide, and bariatric surgeons started paying close attention. Participants on the highest dose lost an average of 28.3% of their body weight over 80 weeks. That figure matches or exceeds what most people lose with bariatric surgery, without going under the knife.
That drug is retatrutide, and Dr. Terry Dubrow – the plastic surgeon and Botched star who spent the past 18 months testing and studying GLP-1 medications, and who recently passed his obesity medicine board exam – has been talking about it loudly and often. His assessment, after personally trying retatrutide for research purposes, is that it is going to change everything. The clinical data is not entirely arguing with him.
Here is what the current evidence says about how it works, what the trials found, and what remains unanswered.
Why This One Is Different From Ozempic and Zepbound
Retatrutide is a triple-agonist drug. Previous weight-loss drugs have been single- or dual-agonist drugs, and that distinction has real consequences for how much weight people lose.
Retatrutide targets three hunger-regulating hormone receptors simultaneously: GIP (glucose-dependent insulinotropic polypeptide), an incretin hormone released after eating that stimulates insulin secretion; GLP-1 (glucagon-like peptide-1), a second incretin hormone that also stimulates insulin release; and glucagon, a hormone secreted by the pancreas that regulates glucose production in the liver. That combination is why it is often called a “triple agonist” or “triple G.”
The glucagon piece is what sets retatrutide apart from everything currently available. Ozempic and Wegovy are single-agonist GLP-1 receptor agonists. Zepbound and Mounjaro target GLP-1 and GIP together, which already made them more effective than single-agonist drugs. Glucagon promotes fat burning even at rest, increasing the calories the body burns between meals – the kind of metabolic shift that dieting alone almost never produces.
Like other modern obesity drugs, retatrutide curbs appetite and slows gastric emptying. The glucagon component also appears to increase energy expenditure, which is why some researchers have started describing it as something like exercise in a jab.
What the Phase 3 Trials Actually Found
The highest dose of retatrutide helped patients lose 28.3% of their weight – or 70.3 pounds – on average over 80 weeks. That is the headline number from the TRIUMPH-1 trial, the large Phase 3 study CNBC reported on in May 2026. Losing nearly 30% of body weight on a weekly injection, without surgery, would have been considered science fiction a decade ago.
The TRIUMPH-1 study involved 2,339 participants randomized to receive retatrutide 4mg, 9mg, 12mg, or placebo. At 80 weeks, participants on 4mg lost an average of 19.0% of their body weight, compared with 25.9% on 9mg, 28.3% on 12mg, and 2.2% on placebo. Even the lowest therapeutic dose produced results that outpace what most people achieve with lifestyle intervention alone.
The TRIUMPH-4 trial, an earlier Phase 3 readout from December 2025, extended the picture further. Participants with obesity and knee osteoarthritis taking retatrutide 12mg lost an average of 28.7% of their body weight at 68 weeks. The TRANSCEND-T2D-1 trial, published in March 2026, showed participants with type 2 diabetes who took retatrutide 12mg lost an average of 16.8% of their body weight at 40 weeks. People with type 2 diabetes typically respond less dramatically to weight-loss medications than people without it, which makes 16.8% at a shorter trial duration a meaningful result.
The Pharmaceutical Journal reported that all doses of retatrutide resulted in clinically meaningful weight loss, while people with severe obesity on the highest dose lost up to 30% of their body weight over two years.
How It Compares to Surgery
The weight loss seen in retatrutide trials exceeds what most people achieve with Wegovy and Zepbound – also known as Ozempic and Mounjaro when prescribed for diabetes – and matches or exceeds what people typically lose with bariatric surgery. UCHealth reported that participants who received retatrutide rather than placebo lost an average of 70.3 pounds over about a year and a half, with more than 45% of participants losing more than 30% of their body weight.
That bariatric comparison is what has Dr. Dubrow – and weight-loss surgeons – paying attention. In his “Dr. and Mrs. Guinea Pig” video series with wife Heather Dubrow, where the couple personally test wellness and health trends, Terry Dubrow described retatrutide as being “45% more effective than any of the other ones that came before it” and predicted it would become the “first trillion-dollar drug when it comes on the market.” Whether or not you take that estimate at face value, the trials are showing this drug operating in a different category than its predecessors.
The average waist reduction was also substantial, with participants losing around 24.1 centimeters from their waistlines. And the benefits are not limited to the scale.
Beyond Weight Loss: Knees, Sleep, Blood Sugar, and Liver Fat
Retatrutide reduced pain for people with knee arthritis by up to 73%, and people who had moderate to severe sleep apnea experienced about 60% fewer events. Those improvements extend well beyond the scale.
Researchers also reported improvements in several cardiometabolic markers, including blood fats, bad cholesterol, blood pressure, and inflammation. These translate into real downstream risk reduction for heart disease, stroke, and diabetes – which is part of why the medical community is watching this drug with an interest that goes beyond its weight-loss numbers alone.
Then there is the liver. In Phase 2, the 12mg dose reduced liver fat by 86%, with 93% of participants achieving normal liver fat levels at 48 weeks. Excess liver fat – formally known as metabolic-associated steatotic liver disease – affects a significant portion of people with obesity and can progress to serious liver damage. A drug that addresses it as a secondary effect is a different kind of tool.
Read More: Retatrutide Trial Results: Most People Lost an Average of 85 Lbs
The Side Effects Worth Knowing About
While drugs such as Wegovy target a single gut hormone, retatrutide aims at three hormone receptors. That increased potency does not come without trade-offs. Scientific American has reported on retatrutide’s increased potency alongside side effects including nausea, diarrhea, constipation, and vomiting.
The most commonly reported side effects are nausea, diarrhea, vomiting, and constipation – consistent with other GLP-1-based medicines – and most participants in trials continued treatment despite these effects. Discontinuation due to side effects rose with dose across the TRIUMPH trials, with higher rates at the 9mg and 12mg doses than at the lowest therapeutic dose.
Approximately 20.9% of patients on the highest dose reported skin sensitivity, tingling, or tenderness to the touch – a condition called dysesthesia. It was generally characterized as mild in the trial data, but it is new territory for this class of drug and something the FDA will likely examine closely during its review.
The weight regain question is also real and unresolved. People who stop taking existing GLP-1 medications tend to regain weight relatively quickly, and there is no reason yet to assume retatrutide will behave differently when discontinued. Long-term follow-up data will eventually answer that question. It does not answer it yet.
What Eli Lilly Is Building Next
Lilly is positioning retatrutide as the next pillar of its obesity portfolio after its injection Zepbound and newly launched pill, Foundayo (orforglipron, the only GLP-1 pill that can be taken any time of day without food or water restrictions, approved by the FDA in April 2026). Novo Nordisk’s CagriSema, a combination of a GLP-1 receptor agonist and an amylin analogue, uses a multi-pronged approach to weight loss and blood sugar regulation, but it is much earlier in development and will take several years before it reaches patients.
A next-generation version of retatrutide itself is already in early development. Scientists are attempting to add a myostatin inhibitor to reta, creating a combination medication that would target GLP-1 and other key hormones while also increasing the body’s ability to build muscle – burning fat and building muscle simultaneously. Dr. Dubrow calls it “the holy grail of weight-loss drugs” and estimates it is about three years from approval.
When You Can Actually Get It
If you are wondering whether to call your doctor Monday morning, the honest answer is: not yet. If the remaining trials are successful, Eli Lilly is expected to submit a New Drug Application to the FDA by late 2026. Under standard review timelines of six to ten months, the FDA could grant approval by the first or second quarter of 2027. More conservative estimates put pharmacy availability at late 2027 or early 2028, depending on how quickly Eli Lilly can manufacture supply and negotiate insurance coverage after an approval.
No FDA-approved branded retatrutide product is commercially available as of 2026. The drug circulates in compounding pharmacies and through online vendors selling it as a research peptide, but these are unregulated and not made to pharmaceutical standards. Compounding pharmacies cannot legally make retatrutide. The only legal access right now is through enrollment in one of the ongoing clinical trials.
Seven additional Phase 3 trials are expected to report results throughout 2026, covering obesity, type 2 diabetes, sleep apnea, MASLD (metabolic-associated steatotic liver disease), and cardiovascular outcomes. Each of those readouts will add to – or complicate – the picture that Eli Lilly needs to build before filing with the FDA.
What Nobody Can Tell You Yet
A 28.3% average body weight reduction across more than 2,300 trial participants is not a fluke or a cherry-picked outlier. It is the highest weight-loss efficacy ever recorded in a pharmaceutical drug trial, in a class of medications that already changed obesity treatment more in five years than the previous five decades did.
What nobody can tell you yet is what happens at 10 years. When someone stops taking it after losing 70 pounds, does the weight come back as fast as it does with existing GLP-1s? What does the dysesthesia signal mean for long-term neurological tolerability at the highest dose? How does it perform in patients with more complicated medical histories? These are not rhetorical concerns. They are the actual questions that a rigorous approval process exists to answer, and they deserve honest acknowledgment alongside the genuinely impressive numbers.
Dr. Dubrow may be right that this drug changes everything. The Phase 3 data is making a reasonable case that he is. But “changes everything” and “available to you right now” are still operating on different timelines, and those two things may not meet until 2027 at the earliest.
Disclaimer: The author is not a licensed medical professional. The information provided is for general informational and educational purposes only and is based on research from publicly available, reputable sources. It is not intended to constitute, and should not be relied upon as, medical advice, diagnosis, or treatment. Always consult a licensed physician or other qualified healthcare provider regarding any medical condition, symptoms, or medications. Do not disregard, avoid, or delay seeking professional medical advice or treatment because of information contained herein.
AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.