Tirzepatide Vs Semaglutide Vs Retatrutide
Tirzepatide vs Semaglutide vs Retatrutide
The short answer
This page is general educational information, research-use framing only, not medical advice. Any decision about a research compound belongs with a qualified clinician.
TL;DR
Comparing tirzepatide vs semaglutide vs retatrutide comes down to how many hormone receptors each one targets and how much weight change each produced in its own trial.
- Semaglutide is a single GLP-1 receptor agonist. In STEP 1, participants lost a mean of 15.3 kg, about 14.9 percent of body weight (Wilding et al., 2021). - Tirzepatide is a dual GIP and GLP-1 agonist. In SURMOUNT-1, the highest dose reached about 22.5 percent mean weight loss (Jastreboff et al., 2022). - Retatrutide is a triple GIP, GLP-1, and glucagon agonist. In a phase 2 trial, it reached up to about 24.2 percent at 48 weeks (Jastreboff et al., 2023). - More receptor targets tracked with larger reported weight change across these separate trials, but the three studies used different designs and cannot be compared head to head. - All three are research compounds here. Any personal use question routes to a qualified clinician.
What is the difference between tirzepatide, semaglutide, and retatrutide?
The difference is how many hormone receptors each one targets: semaglutide hits one, tirzepatide hits two, and retatrutide hits three.
Semaglutide acts on the GLP-1 receptor alone (Wilding et al., 2021). Tirzepatide adds the GIP receptor, making it a dual agonist (Jastreboff et al., 2022). Retatrutide adds a third target, the glucagon receptor, making it a triple agonist (Jastreboff et al., 2023). Each added receptor changes the signaling profile studied in trials, and the reported mean weight change grew as targets were added, though these were separate studies with different lengths and populations.
How do the three compounds compare on the key numbers?
Here is the three-column view of mechanism, peak reported weight change, approval status, and half-life.
| Feature | Semaglutide | Tirzepatide | Retatrutide |
|---|---|---|---|
| Mechanism | GLP-1 agonist | GIP + GLP-1 dual agonist | GIP + GLP-1 + glucagon triple agonist |
| Peak reported weight change | 15.3 kg, about 14.9 percent (Wilding et al., 2021) | about 22.5 percent (Jastreboff et al., 2022) | up to about 24.2 percent at 48 weeks (Jastreboff et al., 2023) |
| Trial | STEP 1, NEJM | SURMOUNT-1, NEJM | Phase 2, NEJM |
| Half-life | about 7 days (Overgaard et al., 2019) | about 5 days (Coskun et al., 2018) | about 6 days (Coskun et al., 2022) |
| Approval status | Approved for named indications by major regulators | Approved for named indications by major regulators | Investigational, no completed phase 3 approval at time of the cited trial (Jastreboff et al., 2023) |
| Dosing frequency studied | Once weekly | Once weekly | Once weekly |
The half-life figures are approximate values that support the once-weekly schedules used in the trials. The weight-change numbers come from three separate studies and are not a direct head-to-head result.
Which one showed the largest weight change in trials?
Retatrutide showed the largest reported figure, up to about 24.2 percent at 48 weeks (Jastreboff et al., 2023), but that came from a phase 2 study, not a comparison against the other two.
In STEP 1, semaglutide produced a mean loss of 15.3 kg (Wilding et al., 2021). In SURMOUNT-1, tirzepatide reached about 22.5 percent at its highest dose (Jastreboff et al., 2022). One head-to-head study, SURPASS-2, did compare tirzepatide against semaglutide directly and reported greater weight reduction with tirzepatide (Frias et al., 2021). No completed trial has placed all three side by side, so the ranking across trials is a rough read, not a controlled result.
How were doses studied in these trials?
Each trial studied fixed once-weekly regimens with a gradual step-up, and this section describes what researchers reported, not a plan for any reader.
In STEP 1, semaglutide was studied at a weekly target after a titration period (Wilding et al., 2021). In SURMOUNT-1, tirzepatide was studied across weekly dose arms up to the highest tested level (Jastreboff et al., 2022). In the phase 2 retatrutide study, participants received weekly doses across several arms (Jastreboff et al., 2023). These are research-reported ranges from named trials. Any decision about a personal dose belongs with a qualified clinician.
What about side effects across the three?
The most commonly reported issues in these trials were gastrointestinal, such as nausea, and they tended to appear during dose step-up.
Across the GLP-1 class, nausea, diarrhea, and constipation were the frequent reported events (Wilding et al., 2021; Jastreboff et al., 2022). Because retatrutide adds a glucagon target, its side-effect and metabolic profile was tracked closely in its phase 2 study (Jastreboff et al., 2023). Separately, one general point on this class: weight tends to return after stopping. STEP 1 extension data reported regain after semaglutide was withdrawn (Wilding et al., 2022), and SURMOUNT-4 reported regain after tirzepatide withdrawal (Aronne et al., 2024). Weight loss on this class also flattens over time rather than continuing forever: in STEP 5, semaglutide weight change was still being tracked out to 104 weeks and had largely plateaued by then (Garvey et al., 2022).
Which comparison page should I read next?
Read the pairwise page that matches the two compounds you are weighing, since each covers its own trial detail.
For a single-target versus dual-target look, see the semaglutide versus tirzepatide page. For the triple versus dual question, see the retatrutide versus tirzepatide page. This hub is the three-way overview; the pairwise pages go deeper on each matchup.
Keep reading
Related research and verification
Tirzepatide Vs Semaglutide Vs Retatrutide: FAQ
References
General educational information only, research-use framing, not medical advice. Confirm the current status where you live and consult a qualified professional before acting.