GLP1 Sema vs GLP2 Tirz: A Beginner’s Comparison Guide

Progression Peptides | progressionpeptides.com

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What Are They?

Both GLP1 Sema and GLP2 Tirz are peptides that work by mimicking hormones your body already produces. Those hormones signal your brain that you’re full, slow down digestion, and help regulate blood sugar.

GLP1 Sema targets one receptor: GLP-1 (glucagon-like peptide-1). Think of it as a single key that unlocks one door. That one door controls appetite and blood sugar signaling.

GLP2 Tirz targets two receptors: GLP-1 and GIP (glucose-dependent insulinotropic polypeptide). Two keys, two doors. The extra GIP pathway adds another layer of appetite and metabolic signaling. Research suggests this dual action is why tirz tends to show stronger results in studies.

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Weight Loss Effectiveness

Both peptides have been studied extensively in large clinical trials.

• GLP1 Sema was studied in the STEP trials, which showed meaningful weight loss results and established sema as a benchmark in metabolic research.
• GLP2 Tirz was studied in the SURMOUNT trials, which generally showed greater average weight loss compared to sema.

The headline: research to date suggests tirz produces more weight loss on average, likely because of its dual-receptor action. That said, individual responses vary. Some researchers see strong results with sema; others find tirz more effective. Both have substantial research backing.

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How They’re Used

Both are administered as subcutaneous injections (under the skin, typically in the abdomen, thigh, or upper arm), once per week.

GLP1 Sema (typical research dosing):

• Starting range: 0.25 mg/week
• Common maintenance range: 1 mg to 2.4 mg/week
• Dose is increased gradually over several weeks

GLP2 Tirz (typical research dosing):

• Starting range: 2.5 mg/week
• Common maintenance range: 5 mg to 15 mg/week
• Also titrated up gradually

Note: these are general ranges seen in research contexts. Exact protocols vary by study and researcher preference.

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Side Effects

Both peptides share a similar side effect profile because they work on the same GLP-1 receptor.

Common for both:

• Nausea (most common, especially early on)
• Mild digestive discomfort, bloating, or constipation
• Reduced appetite (expected, not a side effect per se)
• Fatigue during dose increases

Notable difference: Some studies and user reports suggest GLP2 Tirz produces slightly less nausea relative to its effectiveness compared to sema, possibly due to how the GIP pathway modulates GI effects. It is not dramatically different, but it is worth noting.

Side effects for both tend to be most noticeable when starting or increasing dose, and often settle down over a few weeks.

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Which One to Start With?

There is no single right answer, but here is the general thinking in the research community:

Start with GLP1 Sema if:

• You prefer the most established peptide with the longest research history
• You want to start with something that has more long-term data available
• You are new to GLP-1 peptides and want to see how your body responds

Consider GLP2 Tirz if:

• You want the peptide showing stronger average results in recent trials
• You have tried sema and plateaued or want to explore dual-receptor action from the start

A common pattern: Some researchers start with sema to establish a baseline, then switch to tirz if results plateau. Others go straight to tirz given the stronger efficacy data. Both are valid approaches depending on research goals.

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What to Expect: Timeline

Research timelines vary, but here is a general picture based on studies and user reports:

Timeframe	What Research Suggests
Week 1-2	Appetite reduction begins; some nausea possible
Week 3-4	GI side effects often start to ease; effects more consistent
Week 6-8	Noticeable metabolic effects, early weight changes
Month 3+	More significant results; plateau possible without dose adjustment
Month 6+	Peak results in most trial data

Results are gradual. Research consistently shows that slow, steady titration produces better tolerability and more sustainable outcomes.

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Quick Comparison

	GLP1 Sema	GLP2 Tirz
Receptor targets	GLP-1 only	GLP-1 + GIP
Injection frequency	Once weekly	Once weekly
Starting dose (research)	0.25 mg/week	2.5 mg/week
Avg weight loss (trials)	Significant	Greater on average
Nausea	Common	Slightly less reported
Research history	Longer-established	Newer, strong data

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For Research Purposes Only. GLP1 Sema and GLP2 Tirz are sold by Progression Peptides strictly for laboratory and research use. These products are not intended for human consumption, medical treatment, or therapeutic use. Nothing in this guide constitutes medical advice. Consult a qualified healthcare professional for any health-related decisions.