There’s been a lot of buzz recently about retatrutide — an investigational “triple agonist” peptide that’s shown remarkably large weight-loss effects in early trials.
Here’s TribElle’s clear, patient-friendly breakdown of:
What retatrutide is
What the latest evidence says
What it means for you
Retatrutide (also called LY-3437943) is an experimental, once-weekly injectable peptide being developed by Eli Lilly — the same company behind Mounjaro (tirzepatide).
It’s known as a triple agonist because it activates three different hormone receptors at once:
GIP (glucose-dependent insulinotropic polypeptide)
GLP-1 (glucagon-like peptide-1)
Glucagon receptor
By acting on all three pathways, retatrutide aims to:
Reduce appetite
Increase energy expenditure
Improve glucose and lipid metabolism
🧪 Source: Nature
Retatrutide has completed Phase 2 trials — and the numbers are attention-grabbing:
In a 48-week study, patients on higher doses lost on average 22–24% of their body weight
Even at 24 weeks, mean losses in the mid-teens (percentage) were reported
These results are larger than those typically seen with current GLP-1 drugs like Wegovy or Mounjaro
Beyond weight loss, studies have shown metabolic benefits, including:
Reduced liver fat
Improved lipid levels
Changes in body composition (fat mass loss)
But — and this matters — these are still mid-stage trial results. Phase 3 studies and longer-term safety monitoring are ongoing.
🧪 Sources: Nature, Lilly Investor Relations, The Lancet
So far, the side effect profile looks broadly similar to other incretin-based therapies, including:
Nausea
Vomiting
Diarrhoea
Constipation
Most are mild-to-moderate and occur during dose escalation.
Because retatrutide also activates the glucagon receptor, researchers are closely watching for:
Changes in glucose handling
Shifts in energy metabolism
For now, no unexpected safety concerns have emerged — but longer-term safety data is not yet available.
🧪 Sources: PMC, ScienceDirect
There are no direct head-to-head trials yet, but early signals suggest:
Retatrutide’s higher-dose regimens may lead to greater weight loss than semaglutide or tirzepatide
However, indirect comparisons have limitations:
Different study designs
Different populations
Different durations
Bottom line: we’ll need Phase 3 comparisons and real-world data to truly know how it stacks up.
🧪 Sources: PMC, Lilly Investor Relations
Not yet.
Retatrutide is:
✅ In Phase 3 clinical trials
❌ Not yet approved by any regulatory agency
🚫 Not available for routine prescription or sale
🧪 Source: ClinicalTrials
If you're currently using a licensed GLP-1 or GLP/GIP medication for weight management or diabetes, retatrutide is exciting — but not relevant to your treatment just yet.
Here’s why:
It’s not yet approved
It lacks long-term safety data
And it’s only available in clinical trials
Yes, the trial data is promising. But real-world results, rare risks, and pricing access are still unknown.
If you’re interested in newer therapies or research trials:
Speak to your TribElle prescriber
They can tell you if trials are recruiting and whether participation would suit your medical history
They’ll also help you navigate future options as more medications become available
Retatrutide is one of the most exciting developments in GLP-1 science right now. A triple agonist that’s shown large weight-loss effects and promising metabolic improvements in early trials.
But it’s still experimental.
Until long-term phase 3 data confirms safety and effectiveness, licensed therapies — paired with expert support — remain the best option.
That’s what we’re here for.