Reta-GLP3

Retatrutide, often shortened to RETA, is Eli Lilly’s investigational “triple agonist” weight-loss and metabolic drug designed to activate three hormone receptors at once: GLP-1, GIP, and glucagon. GLP-1 and GIP help regulate appetite, insulin response, and blood sugar, while the glucagon-receptor activity may increase energy expenditure and fat metabolism, which is why RETA is being watched as a potentially more powerful next-generation option than current GLP-1/GIP drugs like tirzepatide.

In clinical trials, retatrutide has shown very large weight-loss results. In a Phase 2 obesity trial, the 12 mg dose produced an average 24.2% body-weight reduction after 48 weeks. More recently, Lilly reported Phase 3 TRIUMPH-1 results where people on 12 mg lost an average of 70.3 lb, or 28.3% of body weight, over 80 weeks, with 45.3% losing at least 30% of their body weight.

It is also being studied beyond weight loss, including for type 2 diabetes, overweight/obesity with related conditions, obstructive sleep apnea, knee osteoarthritis, chronic low back pain, cardiovascular and kidney outcomes, and metabolic dysfunction-associated steatotic liver disease. As of now, retatrutide is still investigational and Lilly says it is legally available only to people enrolled in Lilly clinical trials.

Common side effects reported are generally similar to incretin drugs: nausea, vomiting, diarrhea, constipation, appetite reduction, and other gastrointestinal symptoms. The biggest thing to remember is that RETA is not just “another GLP-1”; it is a GLP-1/GIP/glucagon triple-receptor agonist, which is why people are calling it one of the strongest obesity-drug candidates currently in development.