What happened in retatrutide studies?

Which study findings matter most?

The scale showed the clearest change in the largest published study. In the 48-week stage 2 obesity study, the highest retatrutide amount led to 24.2% average weight loss. Placebo shots without retatrutide led to 2.1% loss ^[1]. The New England Journal of Medicine published the study of 338 people in 2023.

Other studies asked different questions. In one fatty liver group, liver fat fell 82.4% at 24 weeks ^[5]. In a type 2 diabetes group, the average-sugar blood test fell 2.02% ^[2]. You can't combine the figures because the people and study plans differed.

Retatrutide still isn't approved. These are stage 2 findings, while stage 3 TRIUMPH results are not yet published. That is the main limit for you to remember.

What did the Phase 2 obesity study find over 48 weeks?

Study: Jastreboff and coauthors reported it in 2023, journal volume 389, issue 6 ^[1]. People: 338 adults had a weight-to-height number of 30 or more. Some entered at 27 or more with another health problem. No one had type 2 diabetes. Time: 48 weeks, with one shot per week into tissue below the skin.

Average weight change at 48 weeks:

• Placebo, a shot without retatrutide: 2.1% loss
• 1 mg: modest loss
• 4 mg: more loss than the lowest amount
• 8 mg: large loss compared with placebo
• 12 mg: 24.2% loss

Other changes in the 12 mg group:

• Waist size and blood pressure fell.
• The paper reports better blood-fat and fasting-sugar readings.
• No exact figures are given here.

Unwanted effects with the largest amount:

• Constipation, nausea, vomiting, and diarrhea rose with the amount, though most cases were not severe.
• Nausea affected up to 45% at 12 mg.
• Average pulse rose by 5-7 beats per minute and peaked at week 24.
• About 18% left at 12 mg for stomach or bowel trouble.
• About 8% had redness or itching at the injection spot. Group figures can't foretell your result.

What did the Phase 2 type 2 diabetes study find over 36 weeks?

Study: Rosenstock and coauthors reported the work in a 2023 journal, volume 402 ^[2]. People: 281 adults had type 2 diabetes and starting sugar tests within the study's set range. Time: 36 weeks, with weekly shots raised to 12 mg.

Blood sugar at 24 weeks:

• At 12 mg, the average-sugar test fell 2.02%. Placebo fell 0.01%.

Weight at 36 weeks:

• At 12 mg, average weight fell 16.94%. Placebo fell 3.00%.

Safety: Stomach or bowel trouble affected 35%. The study recorded no dangerous sugar drop and no death. Group findings don't predict your result.

What happened in the fatty liver study at 24 and 48 weeks?

Study: Sanyal and coauthors reported this work in 2024 ^[5]. People: 98 adults had fatty liver disease and either obesity or excess weight. Each person's magnetic scan showed liver fat of 10% or more. None had type 2 diabetes. Time: 48 weeks.

Liver-fat change at 24 weeks:

• Placebo: a 0.3% rise
• 1 mg: a 42.9% fall
• 4 mg: a 57.0% fall
• 8 mg: an 81.4% fall
• 12 mg: an 82.4% fall

At 12 mg after 24 weeks, 86% had liver fat below 5% on the scan. At 12 mg and 48 weeks, liver fat had fallen 86.0%. This small study group can't predict your personal result.

What is known about Phase 3 TRIUMPH?

Eli Lilly's stage 3 TRIUMPH work is the larger test needed for retatrutide. No stage 3 finding had been published by mid-2026. TRIUMPH-1/2 cover obesity. Other studies cover type 2 diabetes, heart health, kidney disease, knee arthritis, and sleep apnea ^[10]. One more study compares retatrutide directly with tirzepatide.

News reports mentioned an early TRIUMPH-1 figure of about 28% weight loss. No full paper reviewed by other experts was available. Until that paper appears, the figure remains an early report.

This page gives no stage 3 result because none had been published. That doesn't mean the studies failed. It means the answer was still pending.

What did the combined review find?

In 2025, reviewers combined 3 studies that compared retatrutide with placebo, covering 878 people ^[8]. Across them, retatrutide groups lost an extra 14.33% of starting weight. Side-effect rates did not differ clearly between the groups. The authors did not call the drug safe. The harms seen so far were not unusual for a drug under study, but your long-term risk remained unknown.