The core difference between semaglutide, tirzepatide, and retatrutide is how many hormone pathways each one activates: semaglutide works on one, tirzepatide on two, and retatrutide, the newcomer some call a “GLP-3,” on three. That is also the order of strength in early trial results.
The practical upshot of the retatrutide vs tirzepatide question: retatrutide leads the early trial numbers, but semaglutide and tirzepatide have the longest real-world track record and are the ones you can start today. This guide breaks down how the three compare on weight loss, how they work, and how to pick the right path at Franklin, TN and Nolensville, TN.
The core difference is how many hormone pathways each medication activates. Semaglutide works on one pathway (GLP-1). Tirzepatide works on two (GIP and GLP-1). Retatrutide works on three, adding glucagon, which is why it is nicknamed the triple agonist or “triple-G.” It is also the medication people mean when they say “GLP-3,” a nickname rather than an official drug class. Each added pathway gives the body another way to reduce appetite and, in retatrutide’s case, to increase energy use.
Think of it as a ladder. In a 2023 phase 2 trial in the New England Journal of Medicine, retatrutide’s triple action produced the largest average weight loss reported for this class of medication. More pathways is not automatically better for every person, but it helps explain why retatrutide has generated so much excitement.
In their respective trials, retatrutide produced the highest average weight loss, followed by tirzepatide, then semaglutide. If you are already on tirzepatide and weighing the change, our guide to switching from tirzepatide to retatrutide covers timing, dosing, and the first eight weeks. Retatrutide reached about 24 percent average body-weight loss at 48 weeks in its phase 2 study. Tirzepatide reached about 22.5 percent in the SURMOUNT-1 trial, and semaglutide reached about 15 percent in the STEP 1 trial.
One important caveat: these numbers come from separate studies with different participants and lengths, so they are not a true head-to-head comparison. What they do show is that all three are highly effective, and that tirzepatide, available today, delivers results very close to what early retatrutide studies report.
| Medication | Hormone pathways | Avg. weight loss in trials | Available today? |
|---|---|---|---|
| Semaglutide | 1 (GLP-1) | About 15% | Yes, at Body Works |
| Tirzepatide | 2 (GIP, GLP-1) | About 22.5% | Yes, at Body Works |
| Retatrutide | 3 (GIP, GLP-1, glucagon) | About 24% | Ask our providers |
For most people, the better move is to start now rather than wait. Retatrutide is still working through its phase 3 TRIUMPH research program and where things stand today is worth talking through with a provider rather than guessing from a headline. Waiting means postponing the health benefits you could be gaining now.
Because tirzepatide already delivers results close to early retatrutide data, many people who are curious about retatrutide start with a supervised tirzepatide or semaglutide plan and reassess with their provider as the field evolves. An established relationship makes any future transition smooth. You can read more about how these medications work to decide what fits your goals.
All three medications share a similar side-effect profile because they act on related hormone pathways. The most common effects are digestive, such as nausea, reduced appetite, and occasional stomach upset, especially when first increasing the dose. In the phase 2 retatrutide study in The Lancet, side effects were mostly mild to moderate and tended to ease over time, a pattern also seen with semaglutide and tirzepatide.
This is exactly why medical supervision matters. A provider adjusts your dose gradually, helps you manage any early side effects, and monitors your progress so the plan stays comfortable and effective. Side effects are far more manageable with a personalized, physician-guided approach than with a one-size-fits-all schedule.
The best medication is the one that fits your body, your health history, and your goals, and that decision is easier with expert guidance. Body Works offers physician-supervised medical weight-loss programs with both semaglutide and tirzepatide, and a team that follows the science on retatrutide closely so you always know your best options. Start with the retatrutide (GLP-3) therapy page, or read about retatrutide in Franklin, Nolensville, and for Nashville patients.
With locations in Franklin and Nolensville, you get local, in-person care and a plan built specifically for you. Curious which option is right for you today, and how retatrutide might fit later? Schedule a Free Consultation to map it out. You may also like our guide to keeping the weight off for good.
Our full medical weight loss program is available at both the weight loss clinic in Franklin and weight loss clinic in Nolensville.
Medically reviewed by Dr. Donald Vollmer, MD
Managing Physician, Body Works TN
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