Retatrutide vs tirzepatide — March 2026

SleepDoc_PDX said:

SURMOUNT-1 landed around 20.9% mean weight loss at 15mg over 72 weeks, against roughly 15% for semaglutide 2.4mg in STEP 1.

True, and it depends on a baseline nobody has stated. Without knowing where someone started, the same number can be an excellent result or a disappointing one.

If somebody has the primary source to hand I would rather cite it than paraphrase it.

PharmacoVig_BOS said:

The phase 2 numbers were about 24% mean weight loss at 48 weeks on the top dose, with the curve still descending at the end of the study.

Thank you — that is the clearest version of this I have read, and I have read a lot of them. Sending this to two other people who asked me the same thing last week.

SleepDoc_PDX said:

SURMOUNT-1 landed around 20.9% mean weight loss at 15mg over 72 weeks, against roughly 15% for semaglutide 2.4mg in STEP 1.

This is where I part company with the consensus forming above. The "tirzepatide is simply better" summary irritates me. It is better on mean weight loss, and the cardiovascular outcome evidence is far thinner than semaglutide's. If the reason for treating is cardiovascular risk rather than weight, the evidence base points the other way.

The figures, for anyone assembling their own picture. If you are comparing against somebody else’s result, check that you are comparing the same measurement taken the same way. Most of the apparent contradictions in these threads dissolve at that step.

Moderator note: good thread. Keeping it here rather than moving it, because the question is general enough to be useful. Carry on.