Is Retatrutide the Next Big GLP Thing? Dosage, Benefits, and Comparison to Tirzepatide

Retatrutide is being called the “triple threat” of weight loss drugs—and it’s not even on the market yet. Developed by Eli Lilly, the same pharmaceutical giant behind tirzepatide (better known as Mounjaro and Zepbound), this new contender is generating buzz for its potential to help people lose more weight, faster.

But here’s the catch: retatrutide is still in clinical trials.

So, how are some people already talking about using it? Is that even legal? And how does retatrutide dosage compare to the tirzepatide doses we already know?

In this article, we’ll walk you through what retatrutide is, how it works, what makes it different from tirzepatide, and why the legal and regulatory battle behind the scenes could reshape the future of obesity treatment.

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What Is Retatrutide?

Retatrutide is a once-weekly injectable drug in development by Eli Lilly. It’s part of a growing class of medications known as GLP-1 receptor agonists—a category that includes semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). These drugs mimic gut hormones that help regulate appetite, insulin response, and digestion.

The term GLP-1 stands for glucagon-like peptide-1, a hormone your body naturally produces after eating. It tells your brain you're full, slows down how fast food leaves your stomach, and helps your pancreas release insulin. Drugs in this class harness that effect to help people lose weight and control blood sugar.

Semaglutide works by mimicking GLP-1 alone. Tirzepatide combines GLP-1 with GIP (glucose-dependent insulinotropic polypeptide), a second gut hormone that may improve insulin sensitivity and energy use. That makes it a dual agonist.

Retatrutide goes one step further. It’s a triple agonist, targeting GLP-1, GIP, and glucagon—a hormone that increases calorie burning and promotes fat breakdown. That “tri-agonist” approach may deliver more significant weight loss and health benefits.

However, as of May 2025, retatrutide is still in clinical trials, expected to run through late 2025 or early 2026. Despite rumors and social media speculation, access is currently limited to people enrolled in ongoing studies. Or, people getting it on the GLP-1 Black Market—but we'll get to that later.

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How Retatrutide Works

Retatrutide is designed to activate three hormones—GLP-1, GIP, and glucagon—that regulate appetite, blood sugar, and metabolism. By combining all three into a single weekly injection, the drug aims to deliver more powerful results than current GLP-1 medications. Here’s what early clinical trials suggest so far.

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Significant Weight Loss

In phase 2 studies, participants on the highest retatrutide dose (12 mg) lost an average of 24.2% of their body weight—that’s about 58 pounds in 48 weeks. Notably, the weight loss hadn’t plateaued by the end of the study period, which hints at even greater potential over time. For context, that’s more weight loss than we’ve seen with either semaglutide or tirzepatide so far.

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Improvements in Blood Sugar and Metabolism

People with type 2 diabetes or prediabetes saw real metabolic changes. Up to 82% of participants dropped their HbA1c below 6.5%, and about a third reached below 5.7%, which is considered normal. Retatrutide also improved insulin sensitivity, reduced fasting glucose, and had positive effects on cholesterol and blood pressure—all of which point to a stronger overall metabolic profile.

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Body Fat Reduction and Better Composition

It wasn’t just pounds lost—it was fat lost. Trial participants saw measurable reductions in waist circumference and body fat percentage, which suggests the weight loss wasn’t coming from water weight or muscle mass. That’s important for long-term health and mobility.

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Potential Impact on Obesity-Related Conditions

Early data also showed improved liver enzyme levels, suggesting that retatrutide could benefit people with nonalcoholic fatty liver disease (NAFLD)—a condition often seen in people with obesity or insulin resistance. Other ongoing trials are exploring its potential for sleep apnea, osteoarthritis, and more.

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Works Across Diverse Populations

Weight loss and metabolic improvements were seen across a wide range of participants—different ages, genders, and ethnic backgrounds. That kind of consistency is promising for broader use, if and when the drug is approved.

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Side Effects and Safety

Retatrutide’s side effects look familiar to anyone who’s used GLP-1 meds: mainly nausea, vomiting, or diarrhea, especially during the early dose ramp-up. But overall, the drug was well tolerated, and no major safety red flags emerged during the trials.

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Retatritude Dosage Details

Early clinical trials tested retatrutide doses ranging from 1 mg to 12 mg, given once weekly. The highest dose—12 mg—produced the most dramatic results, with participants losing over 24% of their body weight in just 48 weeks. That level of weight loss is comparable to what some people see after bariatric surgery.

Unlike tirzepatide (Zepbound/Mounjaro), which comes in prefilled pens with doses between 2.5 mg and 15 mg, and semaglutide (Ozempic/Wegovy), which ranges from 0.25 mg to 2.4 mg, retatrutide’s optimal dosage is still being determined. Current trials are testing different doses to figure out the best balance between effectiveness and tolerability.

Drug	Brand Name(s)	Mechanism	Typical Dosage Range (Weekly)	Administration
Retatrutide	None (in trials)	GLP-1/GIP/Glucagon tri-agonist	1 mg, 4 mg, 8 mg, 12 mg (trials)	Injection
Semaglutide	Ozempic, Wegovy	GLP-1 receptor agonist	0.25 mg → 1 mg (Ozempic); up to 2.4 mg (Wegovy)	Injection
Tirzepatide	Mounjaro, Zepbound	GLP-1/GIP dual agonist	2.5 mg → 15 mg	Injection

Because retatrutide activates an additional hormone (glucagon), the dosing may follow a different ramp-up schedule than the dual-agonist or GLP-1-only drugs. Like the others, though, side effects such as nausea and stomach upset tend to appear during the early stages of dose escalation.

Bottom line: retatrutide isn’t a one-size-fits-all drug yet—and the final commercial dosing, if approved, may differ from what’s being used in trials today. However, it will still be an injection.

WHAT ABOUT ORAL GLP-1S? Eli Lilly and Novo Nordisk are each working on their iteration of an oral GLP-1

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Retatrutide vs Tirzepatide: What’s the Difference?

Eli Lilly created both drugs. Both involve GLP-1 and GIP to help regulate appetite, blood sugar, and digestion.

But here’s where they split:

• Tirzepatide is already FDA-approved as Mounjaro (for type 2 diabetes) and Zepbound (for obesity). It’s a dual agonist and available via prescription.

• Tirzepatide was approved as a small-molecule drug and has patent protections until around 2036–2039, depending on the indication.

• Retatrutide is still in clinical trials. It adds glucagon to the mix, which could boost fat-burning and metabolism even further.

• Retatrutide is part of a regulatory tug-of-war. Eli Lilly is pushing for it to be classified as a biologic, which would delay the availability of generics or biosimilars until at least 2037.

This classification could change how long the drug stays protected, and who gets to make cheaper versions later.

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The Turning 'Tides: Which is Better?

With semaglutide, tirzepatide, and now retatrutide, it’s tempting to think more hormones equals better results. But the reality is more complex. Each drug targets different gut hormones to reduce appetite, improve blood sugar, and support weight loss.

Tirzepatide has already demonstrated more weight loss than semaglutide, but both are FDA-approved and available now, and choosing semaglutide doesn’t mean you’re out of luck. It remains a potent and well-studied option with a longer safety track record. For many people, its simpler mechanism means fewer side effects and easier long-term management.

The triple agonist approach may offer broader benefits, but that doesn’t mean it’s automatically better for everyone. More hormones can also mean more side effects—or different ones.

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If Retatrutide Isn't Approved, Why Are People Using It?

There’s already a black market forming around retatrutide, even though the drug hasn’t been approved or legally released. A similar sinister plot is underway with semaglutide and tirzepatide, which spawned from a gray area and not just outright defiance. It's yet another layer of the growing GLP-1 compounding controversy.

Some compounding pharmacies are skirting the rules, claiming to offer versions of the drug based solely on trial data. But unlike semaglutide or tirzepatide—where compounding involves modifying an FDA-approved medication—retatrutide hasn’t been approved at all, making this a clear violation of FDA regulations.

"Retatrutide cannot be used in compounding under federal law. Additionally, it is not a component of an FDA-approved drug and has not been found safe and effective for any condition." - FDA Warning Issued March 17, 2025

The FDA isn't asleep at the wheel on this one either. Numerous warning letters have been sent to suspected shady players.

If you see a clinic or site advertising retatrutide for sale, it’s not legit; at best, they’re misleading you, and at worst, they’re breaking the law.

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The Peptide Revolution Continues

GLP-1 medications like semaglutide, tirzepatide, and retatrutide are part of a larger shift in how we treat obesity and metabolic disease—a movement some are calling the Peptide Revolution.

Semaglutide set the stage. Tirzepatide raised the bar. Now, retatrutide is pushing the edge of what’s possible with its triple-agonist design. But it’s still in trials—and while early results are impressive, we don’t yet know the whole story.

For now, the best option is one that is safe, available, and medically suitable for you. Whether you’re on semaglutide, tirzepatide, or just watching the horizon, it’s clear we’ve entered a new era in treating chronic conditions—and peptides power it.