Educational reference only. Not medical advice. Consult a healthcare provider before starting any protocol.

Library

Retatrutide

Retatrutide (LY3437943)

Weight lossMetabolic healthLiver fat reductionInsulin sensitivity39 amino acids

What it is

A synthetic 39-amino-acid peptide developed by Eli Lilly, engineered as the first triple-agonist targeting GLP-1, GIP, and glucagon receptors simultaneously. Built on a GIP backbone with non-natural amino acid modifications and a C20 fatty diacid moiety for extended half-life. Phase 2 data demonstrated up to −24.2% weight loss at 48 weeks, and Phase 3 (TRIUMPH-4) reported −28.7% at 68 weeks. The glucagon receptor component is studied for its potential role in increasing energy expenditure through thermogenesis and hepatic fat oxidation, differentiating it from dual-agonist approaches.

Community-reported ranges

Clinical trial data from published Phase 2/3 results. Community dosing ranges sourced from forums and mirror trial titration schedules. Not dosing guidance.

Reported dose range

2000–12000 mcg

Estimated half-life

~6 days (144 hours)

Source: Phase 1b/2 clinical data (Urva et al., Lancet 2022; Jastreboff et al., NEJM 2023)

Reported cycle length

24–80 weeks on

not established weeks off

Route

subcutaneous

Common vial sizes

not commercially available

Reported timing

once weekly, any time of day

Reported frequency

1x weekly

Frequently discussed alongside

Based on community forum discussions. Not a recommendation to combine compounds.

Tirzepatide

Compared as dual vs triple incretin agonist in obesity research

Semaglutide

Compared in GLP-1 agonist weight loss contexts

CagriSema

Discussed as competing next-generation obesity pipeline candidates

Published research

Phase 2 obesity trial (Jastreboff et al., NEJM 2023; n=338) demonstrated dose-dependent weight loss of −24.2% at 12 mg over 48 weeks. Phase 2 in T2D (Rosenstock et al., Lancet 2023) showed −16.94% weight loss with HbA1c improvements. A Phase 2a MASLD substudy (Sanyal et al., Nature Medicine 2024) reported liver fat reductions up to −82.4% at 24 weeks. TRIUMPH-4 Phase 3 (n=445, completed Dec 2025) reported −28.7% weight loss at 12 mg over 68 weeks with significant knee OA pain improvements. Community-discussed titration protocols mirror clinical trial design: 2 mg → 4 mg → 8 mg → 12 mg weekly, escalating every 4 weeks. All community use involves unregulated research-grade compounds with significant purity concerns.

Coskun T et al.

Cell Metabolism

Urva S et al.

Lancet

Jastreboff AM et al.

N Engl J Med

Rosenstock J et al.

Lancet

Sanyal AJ et al.

Nature Medicine

Giblin K et al.

Diabetes Obes Metab

Reported side effects

From community self-reports. Not from controlled studies.

Phase 3 (TRIUMPH-4) reported nausea (43%), diarrhea (33%), vomiting (21%), generally mild to moderate and partially mitigated by gradual dose titration. A new safety signal — dysesthesia (abnormal sense of touch) — emerged in TRIUMPH-4 at 8.8% (9 mg) and 20.9% (12 mg) vs 0.7% placebo. Dose-dependent heart rate increases observed, peaking at 24 weeks. Discontinuation rates of 12.2–18.2% in Phase 3.

Regulatory status

FDA (United States)

Not approved. No NDA filed. Phase 3 TRIUMPH program ongoing across 5,800+ participants. NDA filing expected late 2026.

Health Canada

Not authorized. No NDS filed. Clinical trial sites active in Canadian provinces.

WADA (Competitive Athletes)

Prohibited under S0 (Non-approved Substances) at all times. BSCG explicitly names retatrutide as S0-prohibited. GLP-1 agonists as a class are on the WADA Monitoring Program but not prohibited; S0 applies because retatrutide lacks regulatory approval.

Track Retatrutide

Requires free account · 7-day trial included