What do the retatrutide results mean for you?
Phase 1, 2, and 3 found less liver fat, lower weight, and better blood sugar. Other Phase 3 safety tests aren’t finished.
Which retatrutide results matter most?
The strongest published retatrutide result is the large average weight loss. The middle-sized Phase 2 group included 338 adults with obesity.
With 12 milligrams, a measure of drug weight, each week, average weight fell 24.2% in 48 weeks. People given placebo, an inactive shot, lost 2.1% [1].
That result came from Phase 2 and still needs a full Phase 3 answer. Other Phase 3 tests are under way, so Phase 3 has more to tell us.
The first late-stage report followed people with type 2 diabetes and found 15.3% weight loss. It also found a 1.94% drop in a long-term blood-sugar test by 40 weeks [12]; stomach trouble led the harms, and retatrutide remained unapproved.
What did the first small retatrutide study find?
In 2022, 72 adults with type 2 diabetes entered the first small study, which lasted 12 weeks [4]. Each week, a needle put the drug into fat below the skin while doctors watched people closely.
About half the drug remained after 6 days, which fit weekly testing. At the largest amount, people given retatrutide lost 8.96 kilograms more than people given placebo, an inactive shot.
The study’s 90% range ran from 6.75 to 11.16 kilograms, so the exact weight result was still rough. Daily blood sugar also fell at 3 milligrams, and about 63% had stomach or bowel trouble.
The authors found enough promise for more study. The drug then moved into Phase 2, the middle-sized round.
How should you read the Phase 2 result of 24.2%?
The 2023 48-week Phase 2 weight test gave the clearest early result [1]. It followed 338 adults with obesity; some lighter adults joined when they had another health risk.
The study used body mass index, or BMI, a rough number based on weight and height. Adults could join at 30 or more, or between 27 and 30 if they had another health risk.
Just over half the group were men. They used 1, 4, 8, or 12 milligrams each week and also worked on daily habits.
At 48 weeks, the placebo group lost 2.1%. The drug groups lost 8.7% at 1 milligram, 17.3% at 4 milligrams, 22.8% at 8 milligrams, and 24.2% at 12 milligrams.
The 12 milligram amount was the highest tested. In that group, 83% lost more than 15% of their weight, and 26% lost more than 30%.
Stomach or bowel trouble led 18% to quit at 12 milligrams. In 2025, a review called the loss of up to 24% a major step beyond earlier drugs [6].
In 2026, another review said drugs copying two or three body hormones had brought the greatest drug-led weight loss yet [7]. No direct test has settled how retatrutide compares with another drug.
What happened in the Phase 2 type 2 diabetes study?
During 2023, the Phase 2 study followed 281 adults with type 2 diabetes for 36 weeks [2]. Weekly amounts rose in steps to 12 milligrams.
At 24 weeks, the long-term blood-sugar reading fell 2.02% with 12 milligrams, compared with 0.01% after placebo. At 36 weeks, weight fell 16.94%, versus 3.00% with placebo.
Insulin moves sugar from blood into cells; no one who wasn’t taking it needed help for a blood-sugar crash. No one died, and about 35% had stomach or bowel trouble.
In 2026, a review ranked retatrutide highest for weight and blood-sugar change, but only the blood-sugar finding held up when all tests were combined in that larger review [13]. The earlier weight result remains, but you can’t use this review to say retatrutide ranked first among the drugs.
What happened to liver fat in Phase 2?
In the liver study, 98 people had fatty liver disease as well as excess weight. Each began with at least 10% liver fat on an MRI scan [5].
At 24 weeks, liver fat fell 82.4% in the 12 milligram group. MRI uses a large magnet to make detailed pictures, so no cut or surgery was needed.
By then, Normal liver fat below 5% was reached by 86% of the 12 milligram group. By 48 weeks, the 12 milligram group had cut liver fat by 86.0%.
The same scan method measured everyone, but this was still a Phase 2 result. Phase 3 must test whether the large change holds up in wider care.
What did the first Phase 3 diabetes test find?
In 2026, the first Phase 3 result followed 537 adults whose type 2 diabetes wasn’t well controlled by food and exercise [12]. The paper also came out in 2026.
Over 40 weeks, 12 milligrams of retatrutide cut the long-term blood-sugar reading by 1.94% and body weight by 15.3%. Placebo brought drops of 0.81% and 2.6%, so you can compare the groups.
No one using retatrutide alone needed help for a blood-sugar crash. Doctors usually rated the stomach and bowel problems as mild or moderate.
This large study backed the Phase 2 result in one group. Other late-stage tests remain open, and retatrutide vs tirzepatide explains the planned direct comparison.