Tracking a retatrutide schedule
By Tessaro Pty Ltd, the maker of Pepti · Reviewed
This page is about the record, not the regimen. It explains why retatrutide tracking tends to follow a weekly pattern and what a good log captures. It does not contain a dose, a titration amount, or a schedule for you to follow.
What retatrutide is
Retatrutide is an investigational triple agonist, acting on the GIP, GLP-1 and glucagon receptors. It is in Phase 3 clinical trials, its sponsor has said it plans to submit it to the US FDA in the first quarter of 2027 (Eli Lilly, July 2026), and it is not approved by any regulator for any use. Because it is unapproved, there is no label, no authorised dosing, and no clinician-facing guidance for it outside of trial protocols. Anything you have read about what it does or how well it works comes from trial reporting, not from an approved indication, and this page makes no claim either way.
Why the tracking follows a weekly pattern
Structurally, people who log retatrutide log it on a weekly cadence: one entry per week, on the same day, stepping up over time in stages set by whoever directs their use. That shape comes from the trial design and is the reason a log for it looks different from a daily-injection log. Two things follow from it. First, a missed week is a bigger gap than a missed day, so the record needs to make a missed week obvious at a glance. Second, each titration step is a change in what you are doing, and the date of that change is the single most useful fact in the whole history when you look back. To be plain: this page provides no doses and no titration amounts. The figures belong to you and the person directing your use, and the log exists to record what those were, when.
What matters in tracking it
- Consistent day and time — pick the day, pick the clock time, and record the actual time each week. Drift is invisible until it is written down.
- Site rotation — weekly does not mean the site gets a week off by default; it means you have fewer injections to spread across your zones, so it is tempting to reuse the easy one. Follow a fixed sequence; see the rotation guide.
- Reconstitution records — note the water volume and concentration for every vial. A weekly draw from a vial that lasts several weeks is exactly the situation where a forgotten concentration becomes a wrong draw. The free reconstitution calculator on this site converts the figures you already have.
- Weight trend — a weekly weight on the same morning, in the same conditions, alongside the log. The single number never means much; the line over months is the part worth keeping.
- Titration dates — every time the amount changes, log the date it changed. That turns a list of injections into a history you can read.
The record is the point
With a weekly compound, there are relatively few entries, which makes each one matter more. A clean log of day, time, site, vial, weight and any change in step gives you and whoever directs your use something real to look at. The general method is in how to track peptide cycles properly; the reconstitution working is in the reconstitution guide. The peptide tracking app guide covers what a tracker records across a cycle.
What the trials report
Everything known about retatrutide in people comes from trials, so the record you keep sits alongside published numbers rather than a label. In the phase 2 obesity trial, participants received retatrutide or placebo once weekly for 48 weeks; at 48 weeks the mean change in body weight was −24.2 percent in the highest-dose group against −2.1 percent with placebo, and every participant in the two highest-dose groups had lost at least 5 percent (Jastreboff et al., New England Journal of Medicine, 2023). The phase 1b study that preceded it described dose-proportional pharmacokinetics and a half-life of approximately 6 days (Urva et al., Lancet, 2022), which is the pharmacology behind the weekly cadence. A Phase 3 obesity trial published in 2026 (TRIUMPH-1, in adults without diabetes) reports a mean change in body weight of −25.0 percent at 80 weeks in the highest-dose group against −3.9 percent with placebo (Jastreboff et al., New England Journal of Medicine, 2026). In adults with obesity and type 2 diabetes, TRIUMPH-2 reports a mean change in body weight of −18.8 percent at 80 weeks in the highest-dose group against −5.1 percent with placebo (Bellido et al., Lancet, 2026).
Two cautions belong next to those figures. They are group means from a trial population, not a forecast for any one person, and the compound remains investigational, so no regulator has approved it. The retatrutide reference page sets the numbers in context against the approved weekly medicines.
Sources (5)
- Jastreboff et al., New England Journal of Medicine, 2023 — retatrutide phase 2 trial in adults with obesity; 48 weeks, once weekly. PubMed 37366315
- Urva et al., Lancet, 2022 — phase 1b multiple-ascending-dose study of LY3437943 (retatrutide); half-life approximately 6 days. PubMed 36354040
- Jastreboff et al., New England Journal of Medicine, 2026 — retatrutide Phase 3 trial in adults with obesity without diabetes (TRIUMPH-1); 80 weeks. PubMed 42814954
- Bellido et al., Lancet, 2026 — retatrutide Phase 3 trial in adults with obesity and type 2 diabetes (TRIUMPH-2); 80 weeks. PubMed 42810372
- Eli Lilly and Company, press release, 23 July 2026 — topline results from the Phase 3 TRIUMPH-2 and TRIUMPH-3 trials, and the company’s plan to submit a Biologics License Application to the US FDA in the first quarter of 2027 (company announcement, not a peer-reviewed paper). Read on lilly.com
A weekly record, field by field
| Field | What it lets you see later |
|---|---|
| Day and clock time | The gap to the previous entry, so a missed or moved week is visible at a glance. |
| Site, left or right | Whether the sequence is being kept, or one easy zone is being reused. |
| Vial or pen, with concentration and lot | Which batch, and which arithmetic the draw rested on. |
| The figure you were working to | In your own unit, with the date it changed: the history of steps, dated. |
| Weight, same morning each week | The trend line, which is the only part of the number worth keeping. |
| One-line note | Appetite, sleep, anything at the site: the part the numbers cannot hold. |
Common questions
Is retatrutide approved?
No. Retatrutide is an investigational triple agonist of the GIP, GLP-1 and glucagon receptors. It is in phase 3 trials, its sponsor has said it plans to submit it to the US FDA in the first quarter of 2027 (Eli Lilly, July 2026), and it is not approved by any regulator for any use, so there is no label, no authorised dosing and no clinician-facing guidance outside trial protocols.
What is retatrutide's half-life?
Approximately 6 days, from the phase 1b pharmacokinetic study (Urva et al., Lancet 2022). That is the pharmacology behind the once-weekly cadence used in its trials.
Why is retatrutide logged weekly?
Because its trials gave it once weekly: the phase 2 obesity trial administered retatrutide or placebo once weekly for 48 weeks (Jastreboff et al., New England Journal of Medicine 2023), and a half-life of about six days is what makes a weekly interval workable. A weekly log has few entries, so each one matters more, and a missed week needs to be obvious at a glance.
Does Pepti supply a retatrutide dose or titration schedule?
No. Pepti records the figure you already have from whoever directs your use, the date it changed, the site, the vial and your weight. It records the figure you enter; it never calculates or chooses the figure or the step.
This page describes record-keeping only. It does not recommend retatrutide or any other substance, and it provides no dose, titration amount, or schedule. Retatrutide is investigational and not approved for any use.
Pepti’s peptide tracker app keeps the weekly log, the site sequence, the vial records and the weight trend in one place.
Not medical advice. Pepti is a record-keeping tool, not a medical device.
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