Research

What is “GLP-3”? The Next-Gen Weight Loss Nickname Explained

August 24, 20265 min read

If you have spent any time scrolling through health forums or social media recently, you have likely seen a new buzzword taking over the conversation: “GLP-3”.

We all know about GLP-1 medications like Ozempic and Wegovy, which completely transformed how we treat obesity and Type 2 diabetes. Then came “dual-agonist” options like Mounjaro, which hit two different metabolic targets. Now, the internet is buzzing about a third generation.

But what exactly is GLP-3? The short answer is: GLP-3 is a popular, consumer-driven nickname for a new class of experimental “triple-agonist” weight loss medications—most notably Eli Lilly's investigational drug, retatrutide.

Scientifically speaking, there is no such thing as a “GLP-3” hormone or receptor in the human body. Instead, the name caught on as internet shorthand because these new drugs target three distinct metabolic receptors at the exact same time.

The Evolution: From 1 to 3 Receptors

To understand why everyone is calling this new science “GLP-3,” it helps to look at the quick evolution of metabolic therapies over the last few years:

• First Generation (GLP-1 Single Agonists): Medications like semaglutide (Ozempic/Wegovy) mimic a single natural gut hormone called GLP-1. This slows digestion and signals your brain that you are full.
• Second Generation (Dual Agonists): Medications like tirzepatide (Mounjaro/Zepbound) target two pathways: GLP-1 and GIP. Adding GIP further enhances insulin secretion and improves how your body processes fat.
• Third Generation (The “GLP-3” Triple Agonists): This is where retatrutide enters the picture. It keeps the first two helpers (GLP-1 and GIP) and adds a third crucial hormone target: Glucagon (GCG).

The Three Targets of “GLP-3”

By hitting three receptors simultaneously, these investigational molecules tackle weight loss from multiple biological angles at once:

• GLP-1: Suppresses appetite and slows down stomach emptying.
• GIP: Stabilizes blood sugar and optimizes insulin secretion.
• Glucagon: This is the game-changer. Glucagon increases your resting metabolic rate, meaning your body actively burns more calories and handles fat breakdown in the liver much more efficiently.

How It Compares: A Quick Guide

The main difference between the current treatments on the market and the upcoming “GLP-3” class comes down to how many biological buttons the drug can push simultaneously:

What the Data Shows: Just How Effective Is It?

Because of that third glucagon target, retatrutide is showing unprecedented numbers in late-stage clinical trials. Traditional GLP-1 medications typically net an average of 15% body weight loss. Dual agonists push that closer to 21%.

However, recent Phase 3 top-line results from Eli Lilly's TRIUMPH-1 clinical trial programs revealed that participants on the highest weekly dose of retatrutide lost an astonishing 28% to 30% of their baseline body weight over an 80-to-104-week period. For a 230-pound adult, that equates to shedding roughly 70 pounds—a threshold of effectiveness previously only achieved through bariatric surgery.

Beyond raw weight reduction, clinical trial data published in The Lancet indicates massive improvements in blood sugar management. In trials tracking adults with Type 2 diabetes, up to 40% of participants taking retatrutide managed to lower their HbA1c levels below 5.7%—effectively pushing their blood sugar back into the entirely normal, non-diabetic range.

Side Effects and Safety Notice

Unsurprisingly, pushing three biological pathways at once means your body is going to feel it. The side effects of “GLP-3” triple agonists mirror those of standard GLP-1 medications, but can sometimes feel a bit more pronounced during the initial dosage steps:

• Gastrointestinal Issues: Nausea, diarrhea, vomiting, and constipation remain the most common complaints.
• Heart Rate Shifts: Because glucagon revs up the metabolism, some dose-dependent increases in resting heart rate have been noted in trial subjects.

When Will It Be Available?

You cannot get a legal prescription for a “GLP-3” triple agonist just yet. Eli Lilly is currently wrapping up its final Phase 3 clinical trial programs. The manufacturer plans to formally apply for FDA approval in early 2027, meaning the drug could theoretically hit commercial pharmacy shelves by mid-to-late 2027 if it clears regulatory review.

Until then, the only safe, legal way to experience a triple agonist is by qualifying for and enrolling directly in an official, actively open clinical trial.

References

1. Healthline. (2026). The Truth About GLP-3s. Healthline Hub.
2. Noom Medical Insights. (2026). What Is a GLP-3? Retatrutide's Popular Nickname Explained. Noom Blog.
3. Drugs.com. (2026). Retatrutide: Uses, Dosing, Side Effects, and Weight Loss Results. Drugs Reference Guide.
4. Eli Lilly and Company. (2026). Lilly's triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial. Lilly Investor News.
5. Medical Xpress / The Lancet. (2026). New GLP-3 drug significantly slashes both weight and blood sugar. Medical Xpress Feature.
6. GoodRx Health. (2026). Retatrutide for Weight Loss: Availability, Dosage, and More. GoodRx Analysis.