By Judith Wenshuk, peptide research writer
Quick Answer: Semaglutide is the most established compound in the GLP-1 family, with the longest clinical track record of the three major compounds in this category. Trial data (the STEP program) showed average weight loss of around 15% over 68 weeks at the maintenance dose, and it remains the benchmark that newer compounds like Tirzepatide and Retatrutide are measured against.
Semaglutide is where the modern GLP-1 research category effectively started, and it’s still the compound with the deepest body of published data behind it. It’s available in Canada both as a prescription medication and, separately, as a research compound through peptide suppliers.
How It Works
Semaglutide activates the GLP-1 receptor, a single mechanism that affects appetite regulation, gastric emptying, and blood sugar signaling. This single-receptor approach is what later compounds like Tirzepatide (dual-receptor) and Retatrutide (triple-receptor) were built to expand on — but it’s also why Semaglutide has by far the longest history of real-world data behind it.
Typical Research Protocol
The STEP trial program used a gradual escalation over roughly four months:
- Weeks 1–4: 0.25mg weekly
- Weeks 5–8: 0.5mg weekly
- Weeks 9–12: 1mg weekly
- Weeks 13–16: 1.7mg weekly
- Week 17 onward: 2.4mg weekly (studied maintenance dose)
This is a notably slower and more gradual escalation than either Tirzepatide or Retatrutide’s trial protocols, reflecting Semaglutide’s more conservative, longer-established dosing history.
What the Data Shows
In the STEP 1 trial, participants at the 2.4mg maintenance dose averaged approximately 15% weight loss over 68 weeks. That’s meaningfully lower than the headline numbers for Tirzepatide (20–22%) or Retatrutide (up to 28.7%) — but Semaglutide’s trial program is also the largest and longest-running of the three, with more real-world data supporting those numbers than either newer compound currently has.
What People Report
Compared to Tirzepatide and Retatrutide, Semaglutide is frequently described in research communities as the gentlest of the three in terms of side effects — generally less nausea during escalation — though also, consistent with the trial data, the mildest in terms of overall effect size. It’s often the starting point people choose when new to this category, precisely because of that more moderate profile.
How It Compares
For a full breakdown of Semaglutide against Tirzepatide and Retatrutide together, see our three-way comparison guide.
Frequently Asked Questions
Is Semaglutide weaker than Tirzepatide and Retatrutide? In terms of average trial weight-loss outcomes, yes — but it also has the longest safety and efficacy track record of the three.
Why does Semaglutide’s protocol take longer to reach maintenance dose? Its escalation schedule reflects an earlier, more conservative trial design compared to the newer compounds that followed it.
Is Semaglutide available as a research compound in Canada? Yes — Semaglutide is available through research peptide suppliers in Canada, separate from its prescription-drug availability.
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