Retatrutide vs Ozempic, Wegovy and Mounjaro: which is best?
Retatrutide is a triple agonist (GLP‑1, GIP and glucagon) and in trials achieves the largest weight losses (up to 24%), ahead of tirzepatide (Mounjaro, up to 22%) and semaglutide (Ozempic/Wegovy, around 15%). However, retatrutide is still experimental, while the other two are already approved and available on prescription in New Zealand.
The difference is in how many hormones they activate
All three medicines belong to the same family, but represent different generations. The key to understanding them is how many gut hormones they mimic, because that's where their differences in efficacy come from.
- Semaglutide (Ozempic, Wegovy): single GLP‑1 agonist.
- Tirzepatide (Mounjaro): dual agonist of GLP‑1 and GIP.
- Retatrutide: triple agonist of GLP‑1, GIP and glucagon.
Quick comparison
| Medicine | Mechanism | Weight loss (studies) | Available in New Zealand |
|---|---|---|---|
| Semaglutide (Ozempic/Wegovy) | GLP‑1 agonist | ~15% | Yes, on prescription |
| Tirzepatide (Mounjaro) | Dual: GLP‑1 + GIP | Up to ~22% | Yes, on prescription |
| Retatrutide | Triple: GLP‑1 + GIP + glucagon | Up to ~24% | No (experimental) |
The weight loss figures come from different trials and aren't directly comparable with each other, but they give a sense of the trend: each generation adds a mechanism and, with it, greater potential for weight loss.
More weight loss doesn't mean 'better for you'
It's tempting to focus on the highest number, but the best option isn't the one that loses the most weight in a study, but the one that's appropriate and safe for your specific case. Your medical history, other conditions, the side effects you tolerate and, above all, what's approved and available all play a role.
The 'most powerful' medicine on paper is no use if you can't use it legally and under supervision. Today, that rules out retatrutide.
What you can use in New Zealand today
As things stand, the realistic and legal options are semaglutide and tirzepatide. Both have years of evidence, are prescribed with a prescription and are used with medical follow-up to adjust the dose and monitor effects. Retatrutide, however promising, isn't one of them yet.
The sensible way to decide is a medical assessment: a professional reviews your situation and tells you which approved treatment fits you. At DoctorLife that first assessment is free.
Frequently asked questions
Is retatrutide better than Mounjaro or Ozempic?
In trials, retatrutide shows greater weight losses (up to 24%) than tirzepatide (Mounjaro) or semaglutide (Ozempic). But 'better in a study' doesn't equal better for you: retatrutide is still experimental and can't be used, while the other two are already available.
Which one loses the most weight?
According to the available data, retatrutide loses the most, followed by tirzepatide and then semaglutide. Even so, the figures come from different studies and aren't directly comparable, and the response varies greatly from person to person.
Can I choose which medicine to use?
Not directly. They're prescription medicines: the doctor assesses your case and decides which is appropriate and safe for you, adjusting the dose and providing follow-up. Self-prescribing or buying them online is dangerous and illegal.
Why can't I use retatrutide if it's the most effective?
Because it hasn't yet been approved by Medsafe for New Zealand supply and is still in the research phase. Until it completes the trials and receives authorisation, it isn't legally available in New Zealand.
Fuentes
- The New England Journal of Medicine— Triple Hormone-Receptor Agonist Retatrutide for Obesity (phase 2 trial)
- Eli Lilly and Company— Retatrutide: research and clinical development
- Medsafe— Medicines information and safety updates
- European Medicines Agency (EMA)— Search for medicines authorised in the European Union
- EASO— European guidelines and resources on obesity
This guide is part of Losing weight with medical supervision.
