Eli Lilly tests retatrutide triple-hormone obesity drug

Eli Lilly is conducting late-stage clinical trials for retatrutide, an experimental weight-loss drug that targets three hormonal systems: GLP-1, GIP, and glucagon. Unlike current therapies, this triple-agonist approach may influence how the body utilizes energy rather than just suppressing appetite.

In an 80-week study involving individuals with severe obesity and existing cardiovascular disease, participants receiving the highest dose lost an average of 22.6 percent of their body weight. In a separate study involving individuals with obesity but without diabetes, the average weight loss reached 28.3 percent at the highest dose.

While the results are promising, the drug is still in phase three clinical trials and has not yet received regulatory approval. Eli Lilly plans to submit an application for approval in the United States during the first quarter of 2027. Common side effects reported during trials include gastrointestinal issues such as nausea and diarrhea.