Retatrutide vs Mazdutide
A weekly weight-loss injection not yet approved. In trials people lost up to about a quarter of their body weight in 48 weeks. It is a weekly weight-loss shot approved in China. Two trials in over 1,000 adults there showed about 15% weight loss, but no US trial has finished.
Mazdutide has the stronger evidence, grade A (strong human evidence) against grade B for Retatrutide. Neither is FDA approved.
Evidence
BSome human evidence
AStrong human evidence
Human studies cited
Animal or cell studies cited
Why the grade
There is one published randomized phase 2 trial in obesity (338 adults, 48 weeks), a 98-person liver fat substudy of that trial, and one published phase 3 trial, TRIUMPH-2, in 1,152 adults with obesity and type 2 diabetes over 80 weeks; other phase 3 results exist only as press releases. Multiple randomized trials point the same way, but the drug is not approved, most of the roughly 5,800-person TRIUMPH program is unpublished, and there is no long-term safety data, so the grade is B and not A.
Mazdutide has completed multiple phase 3 randomized placebo-controlled trials in China: GLORY-1 in 610 adults with overweight or obesity and GLORY-2 in 461 adults with obesity, plus the DREAMS trials in type 2 diabetes, and it won two approvals on that basis. That meets the A definition. The limits are that nearly all trial participants were Chinese, no cardiovascular outcomes trial has reported, and US data are limited to one phase 2 trial of 179 people.
FDA
In clinical trials
Retatrutide is an investigational drug and is not approved by the FDA for any use. Eli Lilly has said it plans to file for approval in the first quarter of 2027 after completing manufacturing data. Vials sold online as retatrutide are not a legal product; the FDA has stated that unapproved GLP-1 class drugs cannot be used in compounding.
In clinical trials
Not approved by the FDA for any use. Mazdutide is approved in China, where the NMPA cleared it in June 2025 for chronic weight management in adults with overweight or obesity and in September 2025 for glycemic control in type 2 diabetes. In the US it is investigational, with Eli Lilly holding the rights, one US phase 2 trial published and no phase 3 result or FDA filing reported.
Sold for
Retatrutide is talked about as the next step beyond tirzepatide, a triple-hormone injection that produced the largest weight loss yet seen in a drug trial.
Mazdutide is pitched as the next step after tirzepatide: a weekly dual agonist that adds glucagon receptor activity to GLP-1 for more weight loss and liver fat reduction, and it is already being sold by gray-market peptide vendors in the US.
Studies say
Randomized trials show about a quarter of body weight lost over 48 weeks and roughly a fifth over 80 weeks in people with diabetes, with gastrointestinal side effects and heart rate increases, which supports a B pending approval and full phase 3 publication.
Two phase 3 trials in more than a thousand Chinese adults produced about 15 percent weight loss versus placebo over 48 to 60 weeks and led to approval in China, which grades A, although no US trial has finished and no outcomes trial exists.
Class
Triple GLP-1 / GIP / glucagon agonist
GLP-1 / glucagon dual agonist
Route
Injection
Injection