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June 11, 2026Retatrutide, a new weight loss medication is currently in the development stage. The drug works like three gut-hormones to balance metabolism and appetite.
In phase 2 clinical studies, people who used retatrutide on average lost 24% of their initial body weight. Phase 3 trials will confirm the effectiveness of retatrutide for weight loss.
The phase 3 trials for Retatrutide should be completed by early 2026. FDA approval could come as early as 2027.
In recent years, weight-loss injectables have become increasingly popular. Wegovy, Semaglutide and Zepbound are among the most popular medications. It's not hard to understand why, given how effective they are.
Scientists are also researching other medications to help with weight loss. Early studies indicate that certain products under development may be more effective than the ones already available. Retatrutide, a medication that is in development fits into this category.
What is the weight-loss effect of retatrutide? When might FDA approval be granted? We'll discuss 7 things about retatrutide you need to know.
The way Retatrutide is different from other weight loss medications
Retatrutide is similar to Wegovy or Zepbound in that it acts as natural hormones within the body. Retatrutide is a combination of three hormones.
Glucose-dependent insulinotropic polypeptide (GIP)
Glucagon-like peptide-1 (GLP-1)
Glucagon
After eating, GIP and GLP-1 signal to your pancreas that insulin should be released. They lower the amount that your liver produces of glucose (new sugar). GIP-1 and GLP-1 also slow down digestion, which helps you to feel more full. They also target brain areas that influence your food cravings and regulate appetite.
The hormone glucagon tells the liver to produce new sugar. You're not the only one who finds this counterintuitive. Retatrutide helps to keep glucagon under control with its GIP- and GLP-1-activities. The medication does not cause hyperglycemia (high blood sugar).
Glucagon is more than just a sugar-producing enzyme. It can also:
Increase your metabolism
It helps your body to break down fat for energy
The GIP and GLP-1 actions can be enhanced by this additional metabolism boost. This is why the weight loss seems so significant.
Retatrutide, if approved, will be the very first of a brand new class.
In studies, retatrutide caused a weight loss of 24%
Retatrutide may have a significant impact on weight loss, according to studies. After using the highest dose (8mg) of retatrutide, people reported weight losses of 23% to 24% on average. This is more weight loss than other approved medications, and it happens in less time.
Remember that these are results from a clinical phase 2. It's an early-stage trial that was conducted on a small number of participants. A phase 3 study will confirm the effectiveness of retatrutide for weight loss. The study should be completed by early 2026.
More recent results of clinical trials are available, even though they have not yet been approved. In a phase 3 study, people who had osteoarthritis in the knee and were obese were studied. After using retatrutide (12 mg) for approximately 15.5 months, participants lost on average nearly 29% (or 71 pounds) of their initial body weight. The participants also reported significant relief from arthritis and improvements in physical function.
Researchers are also studying retatrutide for the treatment of other diseases
Scientists are also interested in the effects of retatrutide on other conditions. GLP-1 medication has shown benefits in heart health, kidney function, sleep apnea and other conditions.
Researchers are also examining whether Retatrutide is effective in treating:
Type 2 Diabetes
Metabolic dysfunction-associated steatohepatitis (MASH) -- a health condition caused by fat building up in your liver
Chronic kidney disease
Cardiovascular risk reduction
People with large bodies are more likely to develop osteoarthritis in the knee
It's not surprising that medications like GLP-1 can cause this. These conditions are being treated with other GLP-1 drugs.
Retatrutide is likely to be approved as an injection given once a week
Retatrutide was given in its phase three clinical trials as a once-weekly intravenous injection. If it is approved, this will be the dose we see in the market. It's also possible to start at a lower dose, and then gradually increase it over a period of several weeks.
It's not unusual. The majority of GLP-1 drugs are available as injections. Many of these medications also come with weekly dosages, and instructions for dose escalation.
Retatrutide side effects are similar to those of other GLP-1 drugs
Retatrutide has similar side effects to GLP-1 drugs. The most common side effects are gastrointestinal, including:
- Nausea
- Vomiting
- Diarrhea
- Constipation
These side effects were rated as moderate or mild by people who took retatrutide. Side effects became more apparent when the drug was first taken. Serious side effects are rare, as with GLP-1 drugs.
The FDA may approve retatrutide in 2026 and 2027
Eli Lilly cannot apply for FDA approval before phase 3 clinical studies on retatrutide are completed. It is anticipated that this will happen early in 2026. The FDA reviews a product's approval within six to ten months of accepting the manufacturer's application.
This timeframe could allow the FDA to approve retatrutide by 2027. When the FDA approves retatrutide will depend upon the results of the phase three trial, the date the application is submitted by the manufacturer, and the length of time it takes for the FDA to review the request.
Fake retatrutide has been sold but not FDA approved
Approved for effectiveness or safety
People are selling fake retatrutide illegally, just like they do with other weight loss injections. FDA warned people against buying retatrutide in this manner. This medication is not FDA-approved or fully reviewed by its manufacturer.
The risks of using counterfeit drugs, particularly before they are approved, can be numerous. They can include:
It is possible that you receive a product containing a different medicine.
It is possible that you receive a medication-free product.
Experts may not be aware of the risks and side effects associated with unapproved drugs.
It is possible that the device used to administer your medication could fail and lead to injury.
You could receive a product that is contaminated by bacteria, fungi or other germs.
While GLP-1 was in short supply, compounding pharmacies were able to help people get the injections they needed. It's also possible that the supply of retatrutide will be affected if approved. Compounding pharmacies should not be selling medications that aren't approved. It's illegal.
It's best to avoid purchasing retatrutide.
The Bottom Line
Retatrutide, a new weight loss medication is currently in the development stage. This medication mimics three natural hormones. Triple action could help you lose more weight than any other medication. People using retatrutide lost an average of 24 % in weight.
Retatrutide is likely to be offered as an injection given once a week if approved. The side effects of retatrutide are very similar to those experienced by other weight loss injections. Included are nausea, stomach pain, diarrhea and bloating. The FDA will review the retatrutide phase 3 trial and possibly approve it in 2026.
References
Al-Massadi, O., et al. (2019). Glucagon control on food intake and energy balance. International Journal of Molecular Sciences.
American Diabetes Association. (2023). American Diabetes Association highlights novel agent retatrutide which results in substantial weight reduction in people with obesity or Type 2 diabetes during late breaking symposium.
