GLP-1 peptides: the complete Canadian guide
Quick answer
What are GLP-1 peptides?
GLP-1 peptides mimic a gut hormone that reduces appetite and improves blood-sugar control. They are the most-searched compounds in the peptide space because they include the active ingredients of Ozempic, Wegovy, and Mounjaro — and because trial-reported weight loss has climbed with each new generation of the class.
The class, in one idea
After a meal, the gut releases GLP-1GLP-1 (glucagon-like peptide-1)A gut hormone that stimulates insulin release, slows stomach emptying, and reduces appetite. GLP-1 receptor agonists such as semaglutide are studied and prescribed for metabolic regulation.See glossary → — a signal that tells the pancreas to release insulin, the stomach to slow down, and the brain that you’re full. Natural GLP-1 lasts minutes. The engineered versions last about a week, which turns a fleeting signal into a steady one. Each generation of the class adds another receptorReceptorA protein on or inside a cell that binds specific signaling molecules and triggers a response. Most peptides work by binding particular receptors.See glossary → to the design: appetite suppression first, then insulin sensitivity, then energy expenditure.
How the three compounds differ
| Compound | Receptors | Pharma brand | Trial weight change | Canadian status |
|---|---|---|---|---|
| Semaglutide | GLP-1 | Ozempic / Wegovy | −14.9% (STEP 1, 68 wks) | Prescription drug (CA) |
| Tirzepatide | GLP-1 + GIP | Mounjaro / Zepbound | −20.9% (SURMOUNT-1, 72 wks) | Prescription drug (CA) |
| Retatrutide | GLP-1 + GIP + glucagon | None (investigational) | −24.2% (Phase 2, 48 wks) | Phase 3 trials — unapproved |
Weight figures come from separate trials with different durations — directional comparison only, not head-to-head results.
Titration: why every schedule starts tiny
All three compounds slow gastric emptying, and GI side effects concentrate at dose increases. The clinical programs solved this with titrationTitrationStarting at a low dose and increasing gradually on a schedule. Research protocols titrate to assess tolerance — 'start low, go slow.'See glossary →: start at a non-therapeutic dose, hold four weeks, step up only as tolerated. Semaglutide climbs 0.25 → 2.4 mg over 16 weeks; tirzepatide 2.5 → 15 mg over 20; retatrutide arms escalated from 1–2 mg. The schedules are on each compound’s page, and the app’s titration calculators map them to vial concentrations.
Research peptide vs pharmaceutical: the honest difference
- Same molecule, different oversight. Pharmaceutical versions are manufactured under GMP with verified sterility and content. Research vials carry only the vendor’s third-party testing — which is why COACOA (Certificate of Analysis)A lab document reporting what a specific batch actually contains — typically purity by HPLC and identity by mass spectrometry. Reputable research vendors publish batch-specific COAs.See glossary → review is non-negotiable.
- Different formats. Pens deliver fixed doses; research vials are lyophilizedLyophilizedFreeze-dried. Peptides are shipped as a lyophilized powder ('puck') because the dry form is far more stable than a solution. It must be reconstituted before use in research.See glossary → powder requiring reconstitutionReconstitutionThe process of mixing a freeze-dried (lyophilized) peptide powder with bacteriostatic water to create a solution of known concentration.See glossary → and manual measurement — the step where errors happen.
- Different legal categories. Prescription drug vs Research Use Only chemical — covered fully in Are Peptides Legal in Canada?
GLP-1 titration, calculated
The app includes dedicated semaglutide, tirzepatide, and retatrutide titration tools — trial schedules mapped to your vial's actual concentration, with weekly reminders.
The GLP-1 library
Semaglutide
A GLP-1 receptor agonist studied and prescribed for glycemic control and weight management.
Full research profile →
Tirzepatide
A dual GIP/GLP-1 receptor agonist studied and prescribed for glycemic control and weight loss, generally outperforming semaglutide on weight loss in trials.
Full research profile →
Retatrutide
An investigational triple agonist (GIP/GLP-1/glucagon) showing the largest weight-loss figures of the class in Phase 2 trials (~24% at 48 weeks, 12 mg).
Full research profile →
Frequently asked questions
What does GLP-1 mean?
Glucagon-like peptide-1 — a gut hormone released after eating that stimulates insulin, slows stomach emptying, and reduces appetite. GLP-1 drugs are engineered versions of this signal with week-long half-lives.
What is the difference between semaglutide, tirzepatide, and retatrutide?
Semaglutide activates one receptor (GLP-1), tirzepatide two (GLP-1 + GIP), retatrutide three (GLP-1 + GIP + glucagon). Trial-reported average weight loss rises with each: ~15%, ~21%, and ~24% respectively — in separate trials, not head-to-head.
Is research semaglutide the same as Ozempic?
The molecule is the same; everything else differs. Ozempic is a regulated pharmaceutical with verified content and sterility. Research-vendor semaglutide is a Research Use Only chemical whose quality depends entirely on the vendor's testing.
Why do GLP-1 protocols titrate so slowly?
GLP-1 receptor activation slows digestion, and nausea clusters at dose increases. The trial programs stepped doses every 4 weeks to let tolerance develop — the schedules exist because of the side-effect profile.