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Weight & metabolism

Retatrutide

An experimental weight-loss drug still in clinical trials.

StatusInvestigational (phase 3); not approved anywhere
How well studied in peopleTested in clinical trials
Experts quoted7 experts

iNot medical advice. We don’t recommend any dose. Every dose below is a quote from the person named, describing their views or their own use. Retatrutide is an investigational drug. It is not approved anywhere as of October 2026; anything sold outside a clinical trial is unregulated.

What experts say about dosing

9 statements from 5 people. Each one is word for word: we add punctuation only and mark cuts with […]. The chips repeat the exact words used.

Jay CampbellAuthor and podcaster on hormones and peptides; co-founder of a peptide company

Low dose, three times a week

Dose
“0.5mg”
How often
“3x per week”
How long
“8 weeks on, 8 weeks off (or until goal weight reached)”
How taken
“SubQ injection”
When
“AM”

“Dose: 0.5mg. Timing: AM. Frequency: 3x per week. Duration: 8 weeks on, 8 weeks off (or until goal weight reached). Administration: SubQ injection. […] Jay’s Note: If you’ve used semaglutide or tirzepatide and want to understand what comes next — this is it. Start conservatively and respect the cycle structure.”

Read the sourceJay Campbell’s Fat Loss Protocol (jaycampbell.com) · 30 Apr 2026

Context: The card is headed “GLP-3 / Retatrutide”. Retatrutide is still in clinical trials and is not an approved medicine. Quoted from a protocol card on his website (the field labels Dose, Timing, Frequency, Duration and Administration are his). The protocol pages say every protocol has been “personally tested, refined, and used by Jay Campbell”, and most cards link to a product from BioLongevity Labs, a company he co-founded.

Vigorous SteveBodybuilding coach and YouTuber (VigorousSteve)

Microdosing

Dose
not stated
How often
“maybe three times weekly, Monday, Wednesday, Friday”
Also said
“at a low and effective dose”

“It's probably safer to microdose retatrutide or the other GLP-1 receptor agonists, maybe three times weekly, Monday, Wednesday, Friday, at a low and effective dose, just enough to blunt your appetite, promote satiation, and take away the food noise when you're undergoing a cutting phase”

Watch at 7:05How You Should Really Be Using Retatrutide + GLP-1 Agonist Side Effects (VigorousClips) · 7 May 2026 · full video

Context: Contrasted with the once-weekly schedules used for the approved GLP-1 drugs.

Cutting-phase range

Dose
“between 0.25 mg up to 1.66 mg”
How often
“three times weekly, Monday, Wednesday, Friday”
How taken
“subcutaneous”
Also said
“aka 0.75 mg to 5 mg weekly”

“Basically, the sustainable and tolerable dose really depends on how much appetite management you need during a cutting phase, and that could be between 0.25 mg up to 1.66 mg subcutaneous three times weekly, Monday, Wednesday, Friday, aka 0.75 mg to 5 mg weekly.”

Watch at 7:59How You Should Really Be Using Retatrutide + GLP-1 Agonist Side Effects (VigorousClips) · 7 May 2026 · full video

Context: Introduced as his “retatrutide dosing protocols for men and women”. Just before, he notes that side effects in trials were far lower at 1–4 mg weekly than at 12 mg. Clip published on VigorousClips; the same passage is in his full video of 31 Mar 2025, whose captions garble the compound name.

What he sees commonly used

Dose
“3 mg retatrutide weekly split up 1 mg”
How often
“Monday, Wednesday, Friday”

“[…] which again is the commonly used dosage amongst the bodybuilders and everybody else in the fitness community nowadays. 3 mg retatrutide weekly split up 1 mg Monday, Wednesday, Friday, that seems to be the sweet spot for most people using this particular compound.”

Watch at 3:13Is Retatrutide Better Than Tirzepatide? Retatrutide VS Other GLP-1 Agonists (VigorousClips) · 8 May 2026 · full video

Context: Describing common use in the fitness community rather than giving his own recommendation.

Dr Alex TatemBoard-certified urologist and men’s health specialist; YouTube educator

What he says people use (not his recommendation)

Dose
“Start around 1 mg a week”
How often
“a week”

“This is what's being discussed out there, presented so that you, the viewer, can understand the landscape, not so you can replicate it. The single biggest thing to understand is that the community doses retatrutide way lower than the trials did. Where the trials drove people to 4, 9, and 12 mg, the gray market crowd is mostly living around 2 to 4. The recurring pattern in user logs and forums looks like this. Start around 1 mg a week, with cautious ones at 1/2 mg, which is already half or less than the trial starting dose. Then, climb slowly, maybe half to a full mg every 2 to 4 weeks, by feel, rather than a fixed calendar. The reported sweet spot most people settle into is 2 to 4 mg a week, and plenty never go higher.”

Watch at 11:58Retatrutide Dosing Explained (Doctor Breaks Down the Data) (Dr Alex Tatem) · 2 Jun 2026

Context: He describes what he sees reported in user logs and forums and says it is not a recommendation. Earlier in the video he goes through the trial doses (2 mg start, stepped up every 4 weeks to 4, 9 or 12 mg).

Dr Jones DCDoctor of chiropractic (DC); YouTube channel on peptides and GLP-1 medications

His clinic’s starting protocol

Dose
“starts anywhere between 1/2 to 1 mg”
How long
“4 weeks at a half, then 1 mg for another 4 weeks, and then 2 mg”

“Now, the protocol that we use with patients starts anywhere between 1/2 to 1 mg. Maybe a bit more depending on certain circumstances and where they came from. 4 weeks at a half, then 1 mg for another 4 weeks, and then 2 mg. Where most clinics are starting people off from 2 mg on day number one.”

Watch at 4:50Doctor Explains How to Dose Retatrutide to MAXIMIZE Fat Loss (Dr Jones DC) · 14 Jun 2026

Context: What he says his clinic uses. Later in the same video (14:11) he says most people he works with find their ceiling “often in that 2 to 4 mg range”. How often it is injected is not stated in this passage.

Nicholas TrigiliHuman performance specialist and coach; fitness YouTuber

Own use: where the benefits showed up, and the range his clients do best on

Dose
“a half a milligram … 2 milligram … two to four milligram range”
How often
“every two weeks (titration steps)”
How long
“at least 16 weeks (his cycle)”

“I started my first retatrutide cycle around a half a milligram and every two weeks I started titrating my dose up. So I went from a half a milligram all the way up to four milligram even 6 milligram. From a half milligram I went to 2 milligram. That's where the best benefits actually showed up. My appetite came down but it was not zero. […] And this is the same pattern I'd seen with clients over and over and over. The best ones with the best results are the ones that actually stick to like the two to four milligram range. That's the range where you're actually still getting that metabolic and inflammatory benefits without completely destroying your ability to eat.”

Watch at 1:13I’m 39. Here’s Every Peptide I’ve Run So Far in 2026 (Revealing My Protocols) (Nicholas Trigili) · 24 Sep 2026

Context: He started around October–November 2025 and ran it for at least 16 weeks. The cut removes his explanation of the triple-agonist mechanism and a sentence on pushing the dose higher whose figures are unclear in the captions (held for a listen); he says going higher was “not a good idea” and brought bad nausea. He does not state the injection frequency in this passage. He says all the peptides in this video were taken alongside the testosterone and HGH he runs all year. Caption spelling of the compound name corrected: “reatide” → retatrutide. He says in his videos that he is not a doctor.

Own use: how he titrated

Dose
“a half a milligram … up to 4 milligrams”
How long
“over the next six to seven weeks; hold at least 2 weeks”

“I followed that same principle though when I ran my own retatrutide experiment. I actually started much lower than the trials did. I started at a half a milligram and I eventually titrated up to 4 milligrams over the next six to seven weeks. […] You start at your lowest dose. You hold it for at least 2 weeks and you track your weekly loss. Now, if you're landing inside that 1 to 1.5% range and your side effects are still manageable, you do not touch that dose.”

Watch at 1:48Once you start RETATRUTIDE, do these 7 things IMMEDIATELY (Nicholas Trigili) · 9 Oct 2026

Context: Just before, he says: “Before you start anything, talk to your medical professional.” The cut removes a worked example of the 1–1.5% weekly weight-loss target. Caption spelling of the compound name corrected: “reatride” → retatrutide. He says in his videos that he is not a doctor.

How to taper off

Dose
“4 … 2 … 1 … a half a milligram”
How long
“roughly a six week taper”
Break
“taper, don't stop cold”

“Let's say you peaked at 4 milligrams. You don't just stop cold, you taper. Weeks one and two, you drop from 4 milligrams down to 2 milligrams. Weeks three and four, you drop again to like 1 milligram. Week five, you drop to a half a milligram. That's roughly a six week taper from the decision that you decide to come off to your actual last injection.”

Watch at 17:47Once you start RETATRUTIDE, do these 7 things IMMEDIATELY (Nicholas Trigili) · 9 Oct 2026

Context: He says the taper gives the appetite system time to “recalibrate” and avoid rebound hunger. He says in his videos that he is not a doctor.

What experts say about safety

7 statements from 4 people about risks and how strong the evidence is.

Dr Brad StanfieldPrimary-care physician (New Zealand); YouTube educator

Dysesthesia

“This significant jump raises a clear red flag, even though most symptoms were reported as mild and rarely led to discontinuation […].”

Read the source28.7% Weight Loss in New Retatrutide Study (drstanfield.com article) · 18 Dec 2025

Context: About the rate of dysesthesia (abnormal skin sensations) reported with retatrutide in a phase 3 trial, compared with tirzepatide.

Overall view

“Until we have more safety data, tirzepatide remains the more balanced and better-tolerated option.”

Read the source28.7% Weight Loss in New Retatrutide Study (drstanfield.com article) · 18 Dec 2025

Context: Conclusion of his article on the first phase 3 retatrutide results.

Heart rate

“With that rise in metabolic rate comes a dose-dependent rise in resting heart rate — three to seven beats per minute in a phase 2 trial […]. Tirzepatide also raises heart rate, typically two to four beats per minute. That signal is seen across GLP-1-based drugs, but appears more pronounced with retatrutide’s added glucagon activity […]. And the phase-3 retatrutide cardiovascular data is still pending.”

Read the sourceWhy I Take Low-Dose Tirzepatide (Zepbound) (drstanfield.com article) · 1 Jun 2026

Context: From the “Why Not Retatrutide” section of his tirzepatide article. Reference markers replaced by […].

Nicholas TrigiliHuman performance specialist and coach; fitness YouTuber

Nausea and titration

“Nausea is the primary side effect and almost always a titration issue. If you feel nauseated in the first 48 hours after injection, drop back a dose level and hold there for 4 weeks.”

Read the sourceRetatrutide Is Changing Fat Loss in 2026 (Beginner’s Guide) (Biohack Bulletin, Nicholas Trigili) · 22 Jan 2026

Context: Same article.

Dr Ashley FroesePrimary care physician; YouTube channel “This Is Not Covered”

Trial step-up schedule, and her view on microdosing

“I still see a ton of questions around dosing and microdosing GLPs. For retatrutide, in the trials, the doses were 2 mg, 4 mg, 6, 9, and 12 mg spaced out in 4-week intervals, meaning you have to be on one dose for 4 weeks before you can increase. And so you can suppose that that's what's going to be the recommended dosing. But microdosing, I think people are doing this to level out peaks of the medication in their system, meaning if you get really nauseous if you take a GLP, maybe you could microdose it more frequently throughout the week. Sounds solid to me. But, I will say there's a theoretical risk of receptor desensitization”

Watch at 9:09Dr. Explains Why Retatrutide is KING of Fat Loss Peptides (Dr Ashley Froese) · 5 Mar 2026

Context: She describes the trial schedule, not her own protocol, and says just before this that she will not say how to get retatrutide.

Vigorous SteveBodybuilding coach and YouTuber (VigorousSteve)

Taking too much at once

“I do know guys that administered 5 mg, aka an entire vial of retatrutide, in one single shot, and all the gastrointestinal adverse events manifested to the point they could not even hydrate themselves […]. So, uh start low, build your way up so you prevent these terrible side effects”

Watch at 8:25How You Should Really Be Using Retatrutide + GLP-1 Agonist Side Effects (VigorousClips) · 7 May 2026

Context: Anecdote about other people; he adds that he has never spoken to anyone who went up to 12 mg weekly.

Own use

“I either used liraglutide for a couple months, then came off and got fat again, or used tirzepatide for a couple months, came off and got fat again. And now nowadays I use retrotide […]”

Watch at 8:51Is Retatrutide Better Than Tirzepatide? Retatrutide VS Other GLP-1 Agonists (VigorousClips) · 8 May 2026

Context: Own use, no dose given. “Retrotide” is the caption spelling of retatrutide.

Go deeper

What the research used

Context, not a dosing guide. These are the regimens used in randomised trials under medical supervision. The drug is not approved, and these trials do not establish a dose for anyone outside them.

Phase 3 trials

StudyStudied inWhat the study usedWhat it found
TRIUMPH-1: Jastreboff et al., 2026, N Engl J MedPubMed 428149542,339 adults with obesity4, 9 or 12 mg weekly for 80 weeksBody weight −17.6%, −23.7%, −25.0% vs −3.9% with placebo; knee osteoarthritis pain improved
TRIUMPH-2: Bellido et al., 2026, LancetPubMed 428103721,152 adults with obesity and type 2 diabetes4, 9 or 12 mg weekly for 80 weeksBody weight −11.9%, −16.8%, −18.8% vs −5.1%; more diarrhoea, nausea, hypotension and dysesthesia than placebo

Phase 2 trials

StudyStudied inWhat the study usedWhat it found
Jastreboff et al., 2023, N Engl J MedPubMed 37366315338 adults with obesity1–12 mg weekly for 48 weeksBody weight −24.2% at 12 mg; dose-related rise in heart rate
Rosenstock et al., 2023, LancetPubMed 37385280281 adults with type 2 diabetes0.5–12 mg weekly for 36 weeksDose-dependent HbA1c and weight reductions
Sanyal et al., 2024, Nat MedPubMed 38858523Sub-study of adults with fatty liver disease (MASLD)1–12 mg weeklyLarge reductions in liver fat
What we don’t know yet
  • Not approved; long-term and cardiovascular outcome data are still pending.
  • Higher discontinuation and dysesthesia rates than older drugs in phase 3.
  • Split ‘microdose’ schedules described by experts have not been tested in trials.
  • Products sold outside trials are unregulated and may not contain what the label says.
Common questions

Is retatrutide approved?

No. As of October 2026 it is investigational; the manufacturer has said it plans to file with the FDA in 2027.

Why do the expert statements differ from the trial regimens?

The experts describe their own views or what they see in the fitness community; trials test fixed weekly schedules under supervision. We show both but recommend neither.

What side effects have been reported?

Gastrointestinal effects, raised heart rate and dysesthesia. See the trial table and Dr Stanfield’s quotes.

Why does the protocol section only contain quotes?

We do not write our own dose ranges, and retatrutide has no approved dose.

About this page

Word-for-word statements about how retatrutide is being used and about its side effects, each with a link to the source. The phase 2 and phase 3 trials are listed separately as context.

Also known as
LY3437943
Type
Triple GIP / GLP-1 / glucagon receptor agonist
Last updated
11 Oct 2026

Last reviewed 11 Oct 2026 · Compiled by the Peptide Dosing editorial team · How we check quotes