What did mid-sized Phase 2 and larger Phase 3 retatrutide studies find?
Learn what changed for people's weight, hunger, blood sugar, and health, then see which questions doctors haven't settled.
What is retatrutide, and what do doctors know so far?
Doctors are testing retatrutide, a new drug, for obesity and type 2 diabetes. It hasn't been approved anywhere. Here you'll learn what changed, what harm appeared, and what remains unknown, so you can judge what the early findings do and don't mean for you and your health today.
The drug copies messages from three hormones made in your body. GLP-1 starts in the gut; it can ease hunger and help with blood sugar. Glucagon may lead your body to draw on stored fuel.
The main 48-week test was mid-sized, a stage doctors call Phase 2. At the largest amount, average loss was about 24% of starting weight. Another group received a placebo shot containing no retatrutide, which gave doctors a fair comparison.
The maker is now running larger Phase 3 tests with more people. Those tests must confirm both benefit and harm before approval is possible. You won't find a clinic or shop here.
What changed for people in the first retatrutide studies?
Retatrutide is a 39-amino-acid chain, meaning a chain of linked protein pieces. It copies GLP-1, a gut hormone tied to hunger and blood sugar. The GLP-1 message joins two others that may affect insulin and stored fuel.
The main 48-week weight study was short and included 338 adults with obesity. With 12 mg, their average body weight fell −24.2%. People given a placebo shot without retatrutide lost −2.1% [1].
Another Phase 2 study, a mid-sized test, included 281 adults with type 2 diabetes. With 12 mg, their three-month blood sugar average fell −2.02 points after 24 weeks. Their weight fell −16.94% after 36 weeks [2].
The first test in people was small and lasted 12 weeks. After about 6 days, the blood held half as much of the drug. People at the largest amount lost 8.96 kilograms beyond the average loss in the placebo group [4]. That blood finding led later Phase 2 trials to use weekly shots, but it can't predict the change you might see.
Why might retatrutide copy three hormones at once?
The three hormones have different jobs. GLP-1 can slow the stomach, ease hunger, and tell the pancreas to release insulin as blood sugar climbs. A second gut hormone may add to the GLP-1 effect after meals and may affect stored fat.
Glucagon adds a different effect. It may prompt your body to draw on stored fuel and may lower fat held in the liver. That could help explain part of the early weight change.
One review from 2025 reached a clear but cautious view. The two gut hormones may help people eat less, while glucagon may push stored fuel into use [9]. Work with cells showed retatrutide touching three proteins that normally receive those hormone messages [3]. How retatrutide works explains more, but a cell test can't predict your result.
How did retatrutide change liver fat and eating?
What surprised me was the size of the liver change in one small study. The 48-week Phase 2 test included adults who had obesity and fatty liver, plus other health risks. A special magnetic scan measured liver fat without surgery.
With 12 mg, the amount of liver fat dropped −82.4% after 24 weeks. Afterward, 86% had less than 5% liver fat, the level doctors call normal [5]. At week 48, the drop was −86.0% with 12 mg.
A 2025 study also asked people about hunger and eating while taking retatrutide [8]. After the Phase 2 trial, 31 of 36 people noticed a change within 8 weeks [10]. They felt less hungry, ate smaller meals, and felt more in charge of eating. Those words describe their experience; the scan shows the change in their livers.
What can the retatrutide findings tell you today?
Retatrutide copies the work of three body hormones. In a Phase 2 study, a mid-sized test, people ate less and handled blood sugar better. Average weight fell −24.2% at 48 weeks [1]. In another Phase 2 study of type 2 diabetes, the change was −16.94% at 36 weeks [2].
Reviewers in 2025 called the roughly 24% loss a large step beyond older drugs [6]. Yet a study average isn't a forecast for you. Your age, health, medicines, and daily habits can all change both the benefit and the harm.
Larger Phase 3 tests haven't finished. Without FDA approval, retatrutide isn't something your doctor can prescribe. For now, these are findings about a study drug, not a treatment you can receive.