Retatrutide: What Phase 1, 2, and 3 Measured

Studies found weight loss and stomach trouble

Studies are testing retatrutide in people. The FDA hasn’t approved the drug. You can’t get it by prescription. The studies aren’t finished.

Retatrutide acts like three hormones your body makes. Hormones carry instructions between parts of your body. The drug may curb hunger, help insulin, and use stored fuel.

In Phase 2, people lost about 24% on average. The study ran for 48 weeks. Your weight could change in another way.

Nausea and vomiting were common. Higher study amounts raised the resting pulse more. Half the drug left blood over about six days.

Studies still follow heart and kidney health. They haven’t answered the long-term safety questions.

The numbers here come from published studies. The effects page also includes personal reports. Those reports weren’t checked in a controlled study.

Phase 1 measured the drug’s time in blood. Phase 2 measured health changes. Phase 3 is watching more people for longer.

No study knows how your body will respond. It can’t choose care for you.

Your doctor knows your health and medicines. A study average doesn’t.

You’re more than an average.

Phase 2 found large weight and blood sugar changes

In 2023, one study followed 338 adults. All were living with obesity. Some had another illness linked to excess weight. The study lasted forty-eight weeks.

At 12 mg, average weight fell by 24.2%. People given a placebo lost 2.1% ^[1]. A placebo is a sugar pill used for a fair test.

A second 2023 study followed people with type 2 diabetes. The blood test shows average sugar over about three months. At 12 mg, that result fell by 2.02 points. That was a large fall on this blood test.

At 24 weeks, the placebo group changed by 0.01%. At 36 weeks, average weight fell by 16.94%. The placebo group lost 3.00% ^[2].

In 2022, a small study measured time in blood. Half the retatrutide was gone in 6 days ^[4]. At 12 weeks, the highest group lost 8.96 kg more than the placebo group.

In 2025, a review covered 53 weight studies. Retatrutide remained in Phase 3. Across Phase 2 drugs, weight loss ranged from 7.4% to 24.2% ^[11].

Those figures describe whole groups. They can’t predict what your body would do.

Retatrutide copies hormone instructions tied to meals. This might account for the results.

The studies involved obesity and diabetes. The review compared those results with other weight drugs.

The early study was small. Later studies followed more people for longer.

Your body isn’t a group average. Your doctor will start with your own health.

Doctors compared each person’s weight with height. A result of 30 meant obesity. Some people entered at 27 because they also had an illness linked to weight. Phase 1 tested people first. Another Phase 1 study measured time in blood. Phase 2 then measured weight. Phase 2 also measured diabetes. A Phase 2 review compared these drugs. Phase 3 came next.

Your health is your own.

Retatrutide may change hunger, blood sugar, and fuel use

Your gut and pancreas release hormones after meals. Retatrutide acts like three of those hormones ^[6]. Each action starts work inside certain cells.

One action may curb hunger for you. Another helps your pancreas send out insulin when sugar climbs. The third tells your liver to release stored fuel.

In 2024, close lab images showed retatrutide attached in all three places where those hormones work ^[3]. A lab picture can’t prove a benefit in people.

In 2025, one review linked the third action with more fuel use. The authors thought this might account for the weight loss ^[6]. The review couldn’t prove what caused the change in you.

Tests in cells found unequal strength across the three actions. The same review described weight loss near 24%. Neither finding tells you how you’ll respond.

Your health must guide your care. A cell test can’t do that.

Phase 1 measured time in blood. It didn’t test the close cell pictures.

You know your body best.

Retatrutide cut liver fat in one study

A smaller Phase 2 study measured liver fat. It included 98 people with at least 10% liver fat. Doctors used a scan, so no surgery was needed.

At 12 mg, liver fat fell 82.4% by 24 weeks. The placebo group changed 0.3% ^[5]. By 48 weeks, the drop was 86.0%.

At 24 weeks, a normal level was reached by eighty-six percent. The study called anything below 5% normal ^[5]. Your liver might not respond the same way.

One 2025 review found early signs of help for fatty liver and sleep apnea. It found no firm result for bone health, memory, or lasting soreness and swelling ^[10].

Retatrutide hasn’t proved those hoped-for gains. Studies of hearts and kidneys remained open in mid-2026 ^[11].

The study also checked one 12-mg group at 12 weeks. Larger Phase 3 studies aren’t done. They can’t foretell your liver change.

One study can’t settle your risk. Your doctor still knows you best.

Your history belongs in the choice.

Retatrutide isn’t FDA approved

Retatrutide still has no FDA approval. It remains investigational. A doctor can’t prescribe the drug.

The TRIUMPH Phase 3 studies are still running. They include obesity, type 2 diabetes, heart health, and kidney disease. You may never see the drug approved.

Some people call retatrutide “GLP-3.” That isn’t a medical name. Your body has no hormone action called that.

See Retatrutide research for each health result. See retatrutide half life for the time it stays in blood.

The medicine acts like three hormones. Another Phase 3 result is still due. A study listing doesn’t mean approval.

These results can’t promise what happens to you. They can’t direct your care.

Phase 1 began the tests in people. That stage didn’t make the drug approved.

You’ll need care built around you.