You’ve heard of Wegovy and Mounjaro, but what about retatrutide? It’s a brand new weight loss injection that’s currently being developed by Eli Lilly, who also make Mounjaro.
While retatrutide hasn’t been approved yet—which means that a clinician can’t prescribe it to you—the results we’ve seen so far in clinical trials are impressive. So, what is retatrutide and how does it work? Read on to find out
What is retatrutide?
It’s a weight loss medicine that’s taken weekly, like Wegovy and Mounjaro weight loss injections.
But it works in a slightly different way. All of these injections make you feel full by acting like your body’s natural hormones. Wegovy acts like GLP-1 whereas Mounjaro mimics GLP-1 and GIP.
Retatruide takes things a step further by acting like three hormones—GLP-1, GIP, and GCG—earning it the nickname “triple G”. This triple effect probably explains why retatrutide has driven more weight loss in clinical research than currently available weight loss medications.
How does retatrutide work?
Retatrutide makes you feel full by bringing on the effects of these three hormones:
- GLP-1 stimulates the release of insulin, slows your digestion, and helps suppress your appetite.
- GIP enhances insulin release and may work to prevent fat buildup.
- GCG, a.k.a glucagon, may increase the amount of energy your body uses while helping to burn fat.
What is retatrutide used for?
It’s likely to be approved for weight loss initially, but it’s also being studied as a treatment for type 2 diabetes.
What are the potential side effects of retatrutide?
In clinical research, the most commonly reported symptoms were nausea, diarrhoea, vomiting, and constipation. It’s a similar list to both Wegovy and Mounjaro's side effects.
However, because retatrutide is so potent, some people have reported losing weight too quickly.
It’s not good for you to drop lots of weight really fast, and we don’t recommend it. Among other things, it can lead to muscle loss, which can in turn cause bone fractures. Remember, when it comes to weight loss, slow and sustainable is best!
Retatrutide vs other weight loss medications
We’ve touched on this already, but just to reiterate: Retatrutide brings on the effects of three hormones rather than two (Mounjaro) or one (Wegovy). That suggests that it’s the most potent medicine of the lot.
Retatrutide clinical trials
Retatrutide is currently being investigated in a late-stage (phase III) clinical trial for obesity. The trial is due to end in May 2026.
But we can look at completed phase II research to get an idea of retatrutide weight loss results. Here, people on the highest dose of the medicine lost 24.2% of their starting weight after 48 weeks. What’s more, 26% of participants lost at least 30% of their initial weight.
With Mounjaro, the mean loss was 25.3% after an 88-week trial. With Wegovy, the mean loss was nearly 15% after 68 weeks for those taking a 2.4mg dose.
When will retatrutide be available?
For retatrutide to be approved in the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) has to review clinical trial results and confirm that it’s safe and effective.
Since that research is due to be completed in mid-2026, we can’t expect retatrutide to be available before then.
Your weight loss journey
Retatrutide might not be on the market yet, but there are plenty of other weight loss medications out there that work brilliantly for those they’re suitable for.
As part of our science-backed weight loss programme, you can get Mounjaro or Wegovy weight loss injections, or orlistat weight loss capsules, posted to you each month. Plus personalised support from our team of coaches.
Our Voy weight loss results truly speak for themselves. Most people lose 10-15% of their starting weight and 97% say they feel more confident.
Take our quiz to see if you’re eligible. It won’t take more than a few minutes.
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