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№ 009

Tirzepatide

Strong weight loss with a cleaner side effect profile than semaglutide. A dual agonist (GLP-1 + GIP), FDA-approved as Mounjaro / Zepbound.

Fat Loss
Evidence: Strong

Tirzepatide: Strong weight loss with a cleaner side effect profile than semaglutide. A dual agonist (GLP-1 + GIP), FDA-approved as Mounjaro / Zepbound. Tirzepatide is the prescription weight-loss drug sold as Mounjaro (diabetes) or Zepbound (weight loss).

FDA ⓘ
Approved
WADA
Not banned
Typical dose
Start 2.5mg weekly
Half-life ⓘ
~5 days
Route ⓘ
Subcutaneous
Schedule
Once weekly
In plain English

Tirzepatide is the prescription weight-loss drug sold as Mounjaro (diabetes) or Zepbound (weight loss). It hits two appetite-control receptors at once. Most users lose 15-20% of body weight over several months. One injection per week.

Status & legalityWhat do these mean? →
Natty? ⓘ
Not natty

Body-comp drug. Most natty federations consider any prescription weight-loss drug disqualifying.

FDA ⓘ
Approved

Approved as Mounjaro (2022, type 2 diabetes) and Zepbound (2023, obesity).

Compounding ⓘ
Approved drug

Available as an FDA-approved drug, not a compounded peptide.

WADA ⓘ
Not listed

GLP/GIP agonists are not currently classified as banned by WADA.

Prescribed ⓘ

Yes, widely prescribed by primary care, endocrinologists, and obesity-medicine specialists.

Before you start

Wear a CGM the first 14 days.

Verify dose response and watch for hypos at higher doses. A two-week sensor (~$80, OTC, no prescription) tells you more about how YOUR body is responding to Tirzepatide than any protocol guide can. Most users wear one and don't again. The first cycle is the one that matters.

Get a CGM →

Who it's for

  • →Users who couldn't tolerate semaglutide
  • →Metabolic-syndrome adults under provider guidance
  • →Long-term weight management

What to expect

  1. Week 1

    Appetite drops. Mild nausea common.

  2. Week 4

    First titration step. ~2-5lb down for most.

  3. Week 8

    Cumulative loss 5-10lb. Side effects taper.

Looking at Tirzepatide? Your next 3 steps

  1. 1Work out your syringe units

    Vial size + BAC water turns into the exact units to draw for Tirzepatide.

    Open calculator →
  2. 2See what to stack & monitor

    The companion supplements and the bloodwork worth tracking on this kind of protocol.

    Bloodwork guide →
  3. 3Save it & ask the Coach

    A free account saves your stack; membership adds the stack-aware AI Coach.

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How it works (mechanism)

Dual agonist hitting GLP-1 receptors (like Semaglutide) AND GIP receptors. The GIP arm adds an additional satiety and insulin-secretion lever, producing stronger weight loss than GLP-1 alone in head to head trials.

Dosing protocol

Members only

Stacks well with

Members only

Stack essentials

Members only

Side effects

01Nausea
02Constipation
03Reflux
04Fatigue
05Underrating protein intake

When NOT to use

  • ⚠MTC / MEN-2 history
  • ⚠Pancreatitis history
  • ⚠Pregnancy / nursing

Bloodwork to monitor

  • • Lipid panel
  • • ALT/AST
  • • A1C if relevant

Common mistakes

  • • Titrating too fast
  • • Not lifting / eating protein during the cut
  • • Stopping cold turkey without a maintenance plan

Drug & supplement interactions

  • ⚠Insulin and sulfonylureas: dose reduction usually needed
  • ⚠Slows gastric emptying, affects oral medication absorption
  • ⚠Oral contraceptives: switch to non-oral method or add barrier method during initial titration
  • ⚠Warfarin: monitor INR

The Pepdex take

Honest take: we'd run Retatrutide over Tirzepatide if you have access. Tirz works, but the GI side effect intensity isn't talked about enough. Most people who quit bail during the 5-10mg titration because the nausea + reflux is rougher than the marketing implies. If you commit to slow titration and lift heavy through it, the body comp result is genuinely impressive. If you don't lift, you lose 25 lbs of mostly muscle and look worse than when you started.

Community patterns

Members only
Free, no account needed

New to Tirzepatide? Grab the starter checklist.

Drop your email and we'll send the one-page starter checklist beginners actually need first. No account needed.

No spam, and we never sell your email. Just the checklist. Email support@pepdex.co to opt out any time.

AI Coach, live sample
Members only
is 250mcg of bpc enough for a knee injury?
For a knee, 250 mcg sub-q daily is the standard working dose and a solid place to start. The trick with BPC is consistency, give it weeks, not days. Inject close to the joint, run it 4-6 weeks, and don't drop below 200 mcg, it tends to stop cracking the threshold reliably down there. If it hasn't moved at all by week 3, that's when adding TB-500 earns its place.
how much bac water for a 10mg reta vial?
3 mL is the standard play for a 10 mg reta vial. That's 3,333 mcg/mL, clean unit math across the titration: 2 mg = 60 units, 4 mg = 120 units, 6 mg = 180 units on a 100-unit insulin syringe. Run 2 mL instead if you want fewer, more concentrated shots (5,000 mcg/mL, so 2 mg = 40 units). Since most people titrate up over ~12 weeks, 3 mL keeps the numbers cleanest.
what should i track on bloodwork for tirzepatide?
Lipid panel, ALT/AST (liver enzymes), and an A1C, baseline before you start then every 3 months. If you've got metabolic-syndrome history, add fasting glucose and insulin so you can actually watch insulin sensitivity improve. You don't need a big hormone panel for a GLP-1.

Ask the Coach anything about Tirzepatide or your own stack. This is it working.

Trained only on Pepdex content. Does the dose math, flags interactions, knows your stack. Won't push vendors, won't pretend to be a doctor.

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Frequently asked

What is Tirzepatide?+
Tirzepatide is the prescription weight-loss drug sold as Mounjaro (diabetes) or Zepbound (weight loss). It hits two appetite-control receptors at once. Most users lose 15-20% of body weight over several months. One injection per week.
Is Tirzepatide FDA approved?+
Approved as Mounjaro (2022, type 2 diabetes) and Zepbound (2023, obesity).
Is Tirzepatide legal?+
Tirzepatide is FDA-approved and legal to obtain by prescription in the US. Yes, widely prescribed by primary care, endocrinologists, and obesity-medicine specialists.
Is Tirzepatide banned by WADA?+
Tirzepatide is not currently on the WADA prohibited list. GLP/GIP agonists are not currently classified as banned by WADA.
Are you still natty after taking Tirzepatide?+
No. Body-comp drug. Most natty federations consider any prescription weight-loss drug disqualifying.
Do doctors prescribe Tirzepatide?+
Yes, widely prescribed by primary care, endocrinologists, and obesity-medicine specialists.
What's the typical dose of Tirzepatide?+
Dosing depends on your goal, experience, and tolerance. The full Tirzepatide protocol (dose, frequency, and how to titrate) is in the members section on the entry page.
What are the side effects of Tirzepatide?+
Common side effects include: Nausea; Constipation; Reflux; Fatigue. Less common effects and full safety details are on the entry page.
How long until Tirzepatide starts working?+
Appetite drops. Mild nausea common.
What can you stack with Tirzepatide?+
Tirzepatide is commonly combined with complementary compounds. The full stacking protocol (what to pair, dosing, and timing) is in the members section on the entry page.
Where do people get Tirzepatide?+
Pepdex does not sell, ship, or recommend suppliers. Tirzepatide is FDA-approved and dispensed through licensed pharmacies with a prescription; some telehealth clinics prescribe it. If you're vetting a source, /coa explains how to verify a Certificate of Analysis.
Tirzepatide vs Semaglutide, which is better?+
Which is more effective for weight loss, Tirzepatide (Mounjaro / Zepbound) or Semaglutide (Ozempic / Wegovy)? Side-by-side on dose, mechanism, side effects, FDA status. Full head-to-head comparison: https://pepdex.co/compare/tirzepatide-vs-semaglutide
Tirzepatide vs Retatrutide, which is better?+
Retatrutide vs Tirzepatide: head to head on weight-loss potential, mechanism, side effect profile, and current availability. Full head-to-head comparison: https://pepdex.co/compare/retatrutide-vs-tirzepatide
Tirzepatide vs Cagrilintide, which is better?+
Tirzepatide vs Cagrilintide: GLP-1 + GIP appetite control vs amylin pathway. Two different levers on hunger. Full head-to-head comparison: https://pepdex.co/compare/tirzepatide-vs-cagrilintide

Head-to-head with Tirzepatide

Compare
Tirzepatide vs Semaglutide →
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Tirzepatide vs Retatrutide →
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Tirzepatide vs Cagrilintide →
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Tirzepatide vs VK2735 →

More in Fat Loss

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Semaglutide

The original weight-loss wave, sold as Ozempic / Wegovy. A GLP-1 agonist.

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Retatrutide

Triple agonist (GLP-1 + GIP + glucagon) from Eli Lilly. In trials it outperforms Tirzepatide for weight loss.

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Liraglutide (Saxenda / Victoza)

Daily GLP-1 receptor agonist. FDA-approved 2010 (Victoza, T2D) and 2014 (Saxenda, obesity). The first wave of modern GLP-1 weight-loss therapy and direct predecessor to Semaglutide.

№ 023
Cagrilintide

An appetite-control shot for weight loss. A long-acting amylin agonist that works on a different pathway than the GLP-1 drugs, often paired with Semaglutide as 'CagriSema' to break GLP-1 plateaus.