Semaglutide
Semaglutide is a GLP-1 receptor agonist approved by the FDA as Ozempic (type 2 diabetes) and Wegovy (weight management). It reduces appetite and slows gastric emptying, producing an average of roughly 15% body-weight loss over 68 weeks in clinical trials.
What it is
Semaglutide mimics the gut hormone GLP-1, which is released after eating. It activates GLP-1 receptors in the brain and gut to reduce hunger, slow stomach emptying, and improve insulin response. A fatty-acid side chain lets it bind to albumin in the blood, giving it a one-week half-life so it can be injected weekly. Research-grade semaglutide is sold lyophilized in vials and requires reconstitution, unlike branded pens.
What the research says
This is one of the most thoroughly studied peptides in existence.
- STEP 1 trial: 14.9% mean weight loss at 68 weeks vs 2.4% placebo in adults with obesity (PMID 33567185)
- SELECT trial: 20% reduction in major cardiovascular events in adults with overweight/obesity and existing cardiovascular disease (PMID 37952131)
- SUSTAIN trials: reductions in HbA1c of 1.5–1.8% in type 2 diabetes
- Weight regain after discontinuation: roughly two-thirds of lost weight regained within a year (PMID 35441470)
Clinical titration schedule (Wegovy label)
| Weeks | Weekly dose |
|---|---|
| 1–4 | 0.25 mg |
| 5–8 | 0.5 mg |
| 9–12 | 1.0 mg |
| 13–16 | 1.7 mg |
| 17+ | 2.4 mg (maintenance) |
Slow titration exists to limit nausea. Skipping steps is the most common cause of severe GI side effects.
Reconstitution tables
3mg vial
| Bacteriostatic water | Concentration | Units for 0.25 mg | Units for 0.5 mg | Units for 1 mg | Units for 2.4 mg |
|---|---|---|---|---|---|
| 1.2 ml | 2.5 mg/ml | 10 | 20 | 40 | 96 |
| 1.5 ml | 2 mg/ml | 12.5 | 25 | 50 | exceeds 1 ml |
5mg vial
| Bacteriostatic water | Concentration | Units for 0.25 mg | Units for 0.5 mg | Units for 1 mg | Units for 2.4 mg |
|---|---|---|---|---|---|
| 2 ml | 2.5 mg/ml | 10 | 20 | 40 | 96 |
| 2.5 ml | 2 mg/ml | 12.5 | 25 | 50 | exceeds 1 ml |
Storage
- Lyophilized: refrigerate. Reconstituted: refrigerate, protect from light, use within 28 days (matching the branded-pen guidance once in use).
Common stacks
- Semaglutide is usually run alone, alongside resistance training and adequate protein for lean-mass retention. Peptide stacks for muscle preservation are discussed but unstudied.
- Retatrutide vs Tirzepatide for the newer multi-agonists.
Side effects reported
Nausea, constipation, diarrhea, fatigue, and reduced appetite are very common early on. Less common but serious: pancreatitis, gallbladder disease, and in animal studies, thyroid C-cell tumors (carries a boxed warning on the label).
Video explanation
Third-party educational video. Not affiliated with PepIQ.
Frequently asked questions
How many units is 0.25 mg of semaglutide?
It depends on concentration. At 2.5 mg/ml, 0.25 mg = 10 units.
How long does a 5mg vial last?
Roughly 4 weeks at the starting 0.25 mg dose, but only 2 doses at the 2.4 mg maintenance dose.
Is research semaglutide the same as Ozempic?
Same molecule in principle, but research vials are not FDA-regulated or tested for purity the way pharmaceutical product is — this is why COA verification matters.
What happens if you stop?
Most of the weight loss reverses within a year in trial data.
Can it be taken daily instead of weekly?
Some protocols split the weekly dose into daily micro-doses to reduce nausea; the half-life makes total weekly exposure similar.
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