What Is a "GLP-3"?
A plain-language guide to the next generation of weight loss medications, what makes them different, and when (if ever) you will be able to take one.
Quick Answer
"GLP-3" is a nickname, not a real drug class. It refers to the next generation of weight loss medications that activate three hormone receptors at once: GIP, GLP-1, and glucagon. The first drug in this class, retatrutide from Eli Lilly, is in Phase 3 trials and is not yet FDA approved. In the pivotal trial, the highest dose produced an average 28.3% body weight loss, the strongest result ever published for a weight loss medication.
GLP-1, Dual Agonists, and "GLP-3" Compared
How many hormone receptors each drug class activates, and what that means for weight loss.
Drugs: semaglutide (Wegovy, Ozempic), liraglutide (Saxenda), orforglipron (Foundayo). Average weight loss: 8 to 17%.
Drugs: tirzepatide (Zepbound, Mounjaro). Average weight loss: 15 to 22.5%.
Drugs: retatrutide (investigational, Eli Lilly). Average weight loss in trials: 19 to 28.3% (not yet FDA approved).
The pattern is clear in the trial data: hitting more receptors tends to produce more weight loss, up to a point. The trade-off is that more receptor activity also tends to mean more gastrointestinal side effects, which is why dose escalation has to be slow.
Where the "GLP-3" Term Came From
GLP-1 has become a household word. Sometime in 2024 and 2025, as Eli Lilly's retatrutide started showing 24% to 28% weight loss numbers in mid-stage trials, the press needed a way to talk about it that signaled "this is different." "GLP-3" stuck. Outlets like Fox News and Scientific American started using the term in headlines. It is not a real pharmacology label. Pharmacologists call retatrutide and drugs like it triple agonists, or sometimes tri-agonists, because they activate three hormone receptors at once.
The shorthand has stuck because it is easier to say. We use both terms on this page so that whichever you searched for, you land in the right place.
What about "GLP-2"?
GLP-2 is a real hormone, but it does not power the dual agonists like tirzepatide. GLP-2 acts mostly in the gut lining (its medical use is for short bowel syndrome, in a drug called teduglutide). The "GLP-2" label is sometimes used informally to describe dual GIP/GLP-1 drugs like Zepbound and Mounjaro, because they hit two receptors, but this usage is not technically accurate. There is no commercial GLP-2 weight loss drug.
The Flagship: Retatrutide
Eli Lilly's once-weekly injection that activates GIP, GLP-1, and glucagon receptors at once.
At the 12 mg dose in the Phase 3 TRIUMPH-1 trial (May 2026), over 80 weeks. For a 200-pound person, that is roughly 57 pounds.
Almost half of patients on the highest dose hit a weight loss threshold previously reserved for bariatric surgery.
The TRIUMPH-1 trial enrolled 2,339 adults with obesity and at least one weight-related health condition (but no diabetes).
Lilly is expected to submit retatrutide for FDA review by late 2026. Standard review is about 10 months. A commercial launch is most likely in 2027 or 2028.
How it works: GLP-1 reduces appetite and slows digestion (same as Wegovy). GIP adds metabolic effects and seems to soften the GI side effects of GLP-1 (this is the dual mechanism Zepbound uses). The third target, glucagon, is what makes retatrutide different: it nudges the body to burn slightly more energy at rest and to break down fat stores. Glucagon on its own would raise blood sugar, but the GLP-1 component holds that in check.
Read our full guide: Retatrutide: trial data, timeline, and safety profile →
Other Drugs in the "Next Wave"
CagriSema
Novo Nordisk's response to Zepbound and retatrutide. CagriSema combines semaglutide (the GLP-1 in Wegovy) with cagrilintide, a long-acting copy of a second hormone called amylin. It is not a "GLP-3." It uses two molecules instead of one, working on two separate appetite pathways. In the Phase 3 REDEFINE 1 trial, CagriSema produced about 22.7% mean body weight loss over 68 weeks, and about 92% of participants lost at least 5% of their body weight. Novo Nordisk filed it with the FDA on December 18, 2025 and expects a decision in the last three months of 2026. The catch: in REDEFINE 4, the one trial that tested it directly against Zepbound, CagriSema lost, 23.0% against 25.5% over 84 weeks. Read our full CagriSema guide →
Orforglipron (Foundayo)
Not a "GLP-3," but worth knowing about: Foundayo is the first daily GLP-1 pill that does not need an empty stomach or a 30-minute wait. FDA approved April 2026. Average weight loss is about 12.4% at the highest dose, less than injectable Wegovy or Zepbound, but for people who cannot tolerate needles, it is the first real alternative.
Survodutide
Boehringer Ingelheim's dual GLP-1 / glucagon agonist (a different combination than retatrutide). Phase 3 data showed about 16.6% body weight loss, less than the company's Phase 2 readout (~19% in completers) had suggested. Still working through Phase 3 readouts. Not expected on the US market before 2027.
Bimagrumab
A monoclonal antibody (not a GLP-1 at all) that targets muscle preservation during weight loss. Lilly is studying it as an add-on to GLP-1s to preserve lean mass. Experimental, not approved.
Should You Wait for a "GLP-3"?
This is the question most readers actually came here to answer. Honestly: no, you should not wait, unless you have a specific reason like a stalled response on a current GLP-1.
Three reasons:
- The timeline is real. Even in the best case, retatrutide will not be commercially available until late 2027 or 2028. That is 18 to 30 months from now. People typically lose the most weight in their first 6 to 12 months on a GLP-1. Waiting that long without treatment is a real cost.
- Existing options are excellent. Zepbound at the highest dose produces 22.5% average weight loss in non-diabetic patients. That is close to retatrutide's 28.3% and the gap may matter less for individual patients than the population average suggests.
- Side effect profile is similar. Retatrutide's GI side effects (nausea, diarrhea, constipation) are comparable to Zepbound and Wegovy at high doses. The trade-off is not "more weight loss for free."
If you are already losing weight steadily on Wegovy or Zepbound, there is no medical reason to wait for the next thing. If you have plateaued at 10% to 15% and are considering options, talk to your prescriber about dose adjustment or switching, not about waiting two years.
If you decide you want to enroll in a retatrutide trial: trials are listed at clinicaltrials.gov. Search for "retatrutide" and filter by your location. Anything sold online as "retatrutide" outside a clinical trial is not FDA approved, has unverified purity, and is illegal to import. Do not buy it.
Start with what's available today.
Browse our directory of 3,318 GLP-1 clinics across all 50 states. Filter by medication, insurance, and telehealth availability to find a prescriber for Wegovy, Zepbound, Foundayo, or any other FDA-approved option.
"GLP-3" FAQs
"GLP-3" is informal shorthand used by news outlets, not a real drug class. It refers to triple agonists, weight loss medications that activate three hormone receptors at once: GIP, GLP-1, and glucagon. The flagship is retatrutide from Eli Lilly, which is in Phase 3 trials and not yet FDA approved.
No. As of 2026, retatrutide is still in Phase 3 trials. Eli Lilly is expected to submit it to the FDA for review by late 2026. Approval and commercial launch are most likely in late 2027 or 2028.
In the Phase 3 TRIUMPH-1 trial (May 2026), people on the 12 mg dose of retatrutide lost an average of 28.3% of their body weight over 80 weeks. About 45% of patients on that dose lost more than 30% of body weight, a threshold previously seen mostly with bariatric surgery.
No. GLP-2 is a real hormone, but it acts mostly in the gut lining (its medical use is for short bowel syndrome). There is no commercial GLP-2 weight loss drug. The term is sometimes used informally to describe dual GIP/GLP-1 drugs like Zepbound and Mounjaro, but this is not technically accurate.
Retatrutide produced larger average weight loss in trials (about 28.3% on the highest dose over 80 weeks) than Zepbound did in SURMOUNT-1 (about 22.5% on the highest dose over 72 weeks). The two were never compared head to head, and the trials ran for different lengths, so treat the gap as a rough guide rather than a measured difference. The trade-off is that we have far less long-term safety and durability data on retatrutide. Side effect profiles (nausea, diarrhea, constipation) are similar.
For most people, no. Even in the best case, retatrutide will not be commercially available until late 2027 or 2028. That is 18 to 30 months from now. Wegovy (about 15% average weight loss) and Zepbound (about 22.5%) are highly effective today. If you are losing weight steadily on a current GLP-1, there is no medical reason to wait.
No, not legally. The only legitimate way to access retatrutide right now is by joining an active clinical trial. Anything sold online as "retatrutide" is not FDA approved, has unverified purity and dosing, and is illegal to sell or import. We strongly advise against gray-market sources.
Besides retatrutide, the most-watched candidates are CagriSema from Novo Nordisk (a semaglutide plus cagrilintide combination, about 22.7% weight loss in the Phase 3 REDEFINE 1 trial, filed with the FDA in December 2025 with a decision expected late in 2026, though it lost a head-to-head trial against Zepbound), survodutide from Boehringer Ingelheim (a dual GLP-1/glucagon agonist with about 16.6% Phase 3 weight loss), and bimagrumab (a muscle-preservation antibody being studied as an add-on to GLP-1s). Foundayo (orforglipron), the first daily GLP-1 pill, was already FDA approved in April 2026.
Medical Disclaimer: This guide is for informational purposes only and is not medical advice. Retatrutide and other "GLP-3" triple agonists discussed here are investigational and not FDA approved. Always consult a qualified healthcare provider before starting, stopping, or switching any medication.