An experimental drug against obesity produced significant weight loss in two new phase 3 trials. Eli Lilly presented these results on July 23, 2026, for retatrutide, a molecule that simultaneously acts on three hormonal pathways related to metabolism.
In one trial, participants with obesity and cardiovascular disease lost on average up to 22.6% of their weight after 80 weeks, with the highest dose tested. In the other, people with type 2 diabetes lost up to 20.8%.
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Retatrutide targets the receptors of GLP-1, GIP, and glucagon. These hormones play a role in controlling appetite, blood sugar, and how the body uses its energy reserves. Their combined activation thus targets several mechanisms involved in obesity.
In diabetic participants, the treatment also reduced the level of glycated hemoglobin, an indicator of blood sugar balance. The reduction reached 1.6 percentage points in the group receiving the highest dose, according to the results reported by the laboratory.
These data, however, remain results announced by the manufacturer. They will need to be examined in detail, then evaluated by health authorities before any possible authorization. Eli Lilly plans to submit an application to the FDA in the first quarter of 2027.
The most frequent side effects were digestive disorders, including nausea and diarrhea. The laboratory also reports a higher number of serious cardiovascular events in a limited subgroup, a result that will need to be studied with more data.
Retatrutide is therefore not yet an available drug. Its results reinforce its scientific interest, but they do not yet allow a definitive comparison of its benefit-risk ratio to already authorized treatments for obesity.