pepdex
← Back to index
№ 003

Retatrutide

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

Fat Loss
Half-life
~6 days
Route
Subcutaneous
Cycle
Open-ended, titrate over 4-6 months
Schedule
Once weekly
In plain English

Retatrutide is the newest weight-loss compound in development at Eli Lilly. It's a stronger cousin of Tirzepatide (Mounjaro / Zepbound) and pulls bigger weight loss in trials, often 20%+ of body weight. One injection per week. Side effects are real, especially in the first few weeks.

Status & legality
Natty?
Not natty
FDA
Not approved

Investigational. In Phase 3 trials with Eli Lilly. Not yet approved.

WADA
Banned (S2)
Prescribed

Not yet available by prescription. Trial-only access through Lilly's clinical program.

Who it's for

  • →People plateaued on Tirzepatide
  • →Users targeting >15% body weight loss
  • →Metabolic-syndrome adults under provider guidance

What to expect

  1. Week 1

    Appetite drops sharply. Nausea common days 2-4.

  2. Week 4

    First titration step. ~3-6lb down for most users.

  3. Week 8

    Steady-state approaching. Cumulative loss 6-12lb depending on dose.

Dosing protocol

Start 2mg sub-q weekly. Titrate by 2mg every 4 weeks based on tolerance. Trials went up to 12mg; most users plateau benefit at 8-12mg.

Stacks well with

Standalone is the norm
Some add MOTS-c during cuts

Side effects

01Nausea (especially first 2 weeks of each titration step)
02Constipation or diarrhea
03Fatigue / lethargy
04Reduced HRV in some users
05Underrating protein intake from low appetite

When NOT to use

  • ⚠History of medullary thyroid carcinoma or MEN-2
  • ⚠Pancreatitis history
  • ⚠Pregnancy / nursing

Bloodwork to monitor

  • • Lipid panel
  • • Liver enzymes (ALT/AST baseline + every 3 mo)
  • • A1C if metabolic context

Common mistakes

  • • Titrating too fast — stick to 4-week steps
  • • Not eating enough protein during the cut (lean mass loss)
  • • Stopping abruptly with no maintenance plan (rebound common)

Owner notes

Personally on 4mg weekly. Nausea profile was rougher than Tirzepatide for me, eased by week 3. Splitting the weekly dose into 2 doesn't help, just spikes side effects.

Educational only. User-specific dosing is between you and a qualified provider.

Frequently asked

What is Retatrutide?+
Retatrutide is the newest weight-loss compound in development at Eli Lilly. It's a stronger cousin of Tirzepatide (Mounjaro / Zepbound) and pulls bigger weight loss in trials, often 20%+ of body weight. One injection per week. Side effects are real, especially in the first few weeks.
Is Retatrutide FDA approved?+
Investigational. In Phase 3 trials with Eli Lilly. Not yet approved.
Is Retatrutide banned by WADA?+
Retatrutide is on the WADA prohibited list under Banned (S2).
Are you still natty after taking Retatrutide?+
No. Retatrutide is a performance-enhancing peptide and would disqualify a strict natty claim.
Do doctors prescribe Retatrutide?+
Not yet available by prescription. Trial-only access through Lilly's clinical program.
What's the typical dose of Retatrutide?+
Start 2mg sub-q weekly. Titrate by 2mg every 4 weeks based on tolerance. Trials went up to 12mg; most users plateau benefit at 8-12mg.
What are the side effects of Retatrutide?+
Common side effects include: Nausea (especially first 2 weeks of each titration step); Constipation or diarrhea; Fatigue / lethargy; Reduced HRV in some users. Less common effects and full safety details are on the entry page.
How long until Retatrutide starts working?+
Appetite drops sharply. Nausea common days 2-4.