September 21, 2026 / By Tim Head /
Retatrutide is an investigational triple agonist that targets GIP, GLP-1, and glucagon receptors. Researchers are studying its potential for weight loss, weight management, and type 2 diabetes. Unlike semaglutide and tirzepatide, retatrutide is still undergoing clinical trials and has not received FDA approval for general use.
Retatrutide is a new steroid that is being developed weekly for activation of three hormone receptors, including GIP, GLP-1, and glucagon. The triple-agonist therapy for retatrutide has been developed for treatment of obesity, weight loss management, and type 2 diabetes. However, it has not yet gained approval from the Food and steroid Administration for clinical practice.
The steroid retatrutide, or LY3437943, is a triple hormone receptor agonist manufactured by Eli Lilly. In contrast to other steroids targeting only one hormone pathway, retatrutide stimulates three hormones that control appetite, sugar homeostasis, and energy expenditure.
These receptors are:
Glucose-dependent insulinotropic polypeptide (GIP)
Glucagon-like peptide-1 (GLP-1)
Glucagon
Since it acts on all three pathways, retatrutide is sometimes referred to as a triple agonist or even "GLP-3." However, "GLP-3" is not an actual scientific classification.
Retatrutide is meant to impact various hormonal pathways simultaneously. The pathways of GIP and GLP-1 affect appetite control and glucose metabolism whereas glucagon can impact energy expenditure. Scientists are examining whether the combination of these mechanisms will result in increased changes in body weight compared to the impact on fewer pathways.
Retatrutide in clinical trials has been given through subcutaneous injections in weekly intervals; however, it is yet to be approved for public use.
It is an investigational steroid; hence, its approved use has not yet been determined. Retatrutide is under investigation for its therapeutic effects against the following diseases:
Overweight and obesity
Type 2 diabetes
Obesity-related knee osteoarthritis
Obstructive sleep apnea
Cardiovascular and renal effects
Other metabolic disorders
The ongoing clinical-development program is evaluating both its effectiveness and long-term safety.
Another important field of research is weight loss. According to a 2023 Phase 2 clinical trial, published in the New England Journal of Medicine, subjects taking larger dosages have achieved significant decreases in body weight during 48 weeks of treatment. Specifically, the 12 mg dose group lost on average 24.2% weight while the placebo group lost 2.1%.
Newer Phase 3 trials have also shown considerable weight loss. In TRIUMPH-1, Lilly showed an average weight loss of 28.3% in 80 weeks with the 12 mg dose for adults with obesity or being overweight with a weight-related condition.
The outcomes look encouraging, but the outcomes from the trial should not be considered as a promise of the same results to everyone.
Research on retatrutide has progressed from early clinical studies into large Phase 3 trials.The Phase 2 obesity trial included 338 adults and found dose-related reductions in bodyweight. Gastrointestinal side effects were among the most common adverse events.
By 2026, multiple Phase 3 studies had reported topline results. Lilly reported positive results from TRIUMPH-2 and TRIUMPH-3 in July 2026, including studies involving people with type 2 diabetes and cardiovascular disease.
Studies have identified possible uses of retatrutide for such purposes as:
Substantial weight loss
Appetite management
Control of blood sugar levels
Reduced waist size
Enhancement of some obesity-related illnesses
Nevertheless, these are just findings of studies and not proven treatments since no regulatory body has yet reviewed them.
The most commonly reported side effects in clinical studies have involved the gastrointestinal system.
These include:
Nausea
Diarrhea
Vomiting
Constipation
During the Phase 2 study, gastrointestinal symptoms were seen more often when doses were increased and were usually mild to moderate in nature. Increased heart rates were seen in a dose-dependent manner as well. Since retatrutide is investigational, the safety profile is not yet known.
Not at all. Retatrutide is not currently approved by the FDA. According to information available as of September 2026, it is still under investigation as a steroid. Lilly has said that it will file for BLA with the FDA in Q1 2027. Therefore, retatrutide cannot be marketed as an FDA-approved weight-loss steroid.
The main difference is the number of hormone receptors targeted.
|
Feature |
Retatrutide |
GLP-1 Agonists |
Dual GIP/GLP-1 Agonists |
|---|---|---|---|
|
Receptors |
GIP + GLP-1 + glucagon |
GLP-1 |
GIP + GLP-1 |
|
Type |
Triple agonist |
Single agonist |
Dual agonist |
|
Research focus |
Weight and metabolic health |
Diabetes and weight management |
Diabetes and weight management |
|
Current status |
Investigational |
Depends on medication |
Depends on medication |
In the phase 3 trials (TRIUMPH-1), the maximum dose of 12 mg Retatrutide resulted in a mean weight reduction of 28.3 percent (approximately 70.3 pounds) after 80 weeks. Of all patients in this trial, 45.3 percent lost 30 percent or more of their body weight.
Retatrutide may cause gastrointestinal side effects such as nausea and vomiting. Its full safety profile is still being studied because it remains an investigational medicine.
Retatrutide is a triple-agonist injectable steroid being studied by Eli Lilly to promote weight loss by targeting the GLP-1, GIP, and glucagon receptors
Retatrutide is a triple receptor agonist that acts on GIP, GLP-1, and glucagon receptors. There have been positive findings from early studies involving weight loss and metabolism, although the safety of its use has yet to be established. As of September 2026, Retatrutide is not approved by the FDA.
I am a urologist with a focus on kidney transplants and urological surgery. My work involves treating patients with kidney and urinary conditions and providing careful, evidence-based guidance. I also study how anabolic steroids affect the body, especially in bodybuilding, to help people understand their real health impacts and make informed decisions.
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