Coach Gary Miller on Retatrutide: His Protocol vs What the Data Shows
Powerbuilding coach Gary Miller published a video titled "Retrutide or GLP-3 for fat loss and muscle retention!" presenting retatrutide as "probably one of the most powerful peptides for body recomposition we've ever seen." After 35 years of personal training and 25 years coaching, Miller offers a suggested protocol combining retatrutide with strength training, high-protein nutrition, and a peptide stack.
This page checks his claims and protocol recommendations against published clinical trial data. Miller states upfront that he is not a doctor and that the video is for educational purposes only.
His Top Claims: Fact Check
Miller lists four key benefits of retatrutide. Here is how each compares to published data:
| Claim | Published Data | Verdict |
|---|---|---|
| 20 to 30 pounds of fat loss in clinical trials | Phase 2: up to 58 lbs (26.3 kg) at 12mg/48wk. TRIUMPH-4: 71.2 lbs at 12mg/68wk | Undersells it — actual results are 2–3x higher |
| Targets deep visceral fat | Phase 2 body composition substudy showed significant visceral fat reduction | Supported by data |
| Stronger appetite suppression than semaglutide or tirzepatide | No head-to-head appetite comparison exists; weight loss data suggests greater effect | Plausible but unproven |
| Muscle preservation when paired with protein and training | DXA substudy: fat-to-lean loss ratio similar to other GLP-1 drugs, not uniquely better | Overstated — not uniquely muscle-sparing |
| Enhances resting energy expenditure | Glucagon receptor activation increases energy expenditure in preclinical data | Mechanistically supported |
The most notable gap is his weight loss claim. Saying "20 to 30 pounds" significantly undersells what the trials actually showed. TRIUMPH-4 reported an average of 71.2 lbs of weight loss at the 12mg dose — more than double his stated range.
For the full trial data, see Retatrutide Results. For the mechanism, see What Is Retatrutide.
His Suggested Protocol
Miller recommends the following:
- Starting dose: 2.5mg weekly (or as low as 1mg)
- Target dose: "7 and 12 to 10 milligrams per week"
- Administration: Subcutaneous, once weekly
- Nutrition: High protein, low inflammatory
- Training: Lift weights 4 times per week
- Cardio: Daily walking, 8,000–10,000 steps
- Peptide stack: Tesamorelin, TB-500, BPC-157, or ipamorelin
| Element | His Recommendation | Clinical Trial Protocol |
|---|---|---|
| Starting dose | 2.5 mg (or 1 mg) | 2 mg in Phase 3 TRIUMPH program |
| Target dose | 7–12 mg | 9 mg or 12 mg (Phase 3 targets) |
| Titration speed | Not specified | Every 4 weeks: 2 → 4 → 6 → 9 → 12 |
| Peptide stacking | Tesamorelin, TB-500, BPC-157, ipamorelin | Not studied — no data on combinations |
| Exercise requirement | 4x/week weights + daily walking | Lifestyle modification counseling in trials |
His dosing recommendations are loosely consistent with clinical trial designs but contain some inaccuracies. The Phase 3 starting dose is 2mg, not 2.5mg, and the target doses are 9mg and 12mg — his "7 and 12 to 10" phrasing is unclear. Most critically, he omits the 4-week titration schedule that Phase 3 trials used to manage side effects. Skipping titration steps is what caused higher dropout rates in Phase 2.
His peptide stack recommendation (tesamorelin, TB-500, BPC-157, ipamorelin) has no clinical evidence when combined with retatrutide. The safety profile of these combinations is unknown.
For clinical dosing guidance, see Retatrutide Dosage. For the titration schedule, see Retatrutide Dosing Schedule.
The "Metabolic Reboot" Claim
Miller describes retatrutide as providing a "metabolic reboot" — enhancing insulin sensitivity, glucose regulation, and resting energy expenditure. He suggests it is a "game changer for those who think they have a slow metabolism."
The insulin sensitivity claim is well-supported: Phase 2 data in patients with type 2 diabetes showed HbA1c reductions of up to 2 percentage points, and the glucagon receptor component does increase energy expenditure. However, the framing as a "metabolic reboot" overpromises. Clinical data shows retatrutide's effects on metabolic markers are dose-dependent and occur alongside weight loss — not as a separate "reboot" phenomenon.
For diabetes-specific data, see Retatrutide for Diabetes.
Frequently Asked Questions
Who is Gary Miller?
Gary Miller is a powerbuilding coach who runs Gary Miller Fitness. He describes himself as having 35 years of personal training experience and 25 years coaching athletes and professionals. He is not a physician or medical researcher. His retatrutide video presents a suggested protocol based on his coaching experience.
Is his protocol safe to follow?
Miller's protocol includes grey market retatrutide combined with multiple unregulated peptides — none of which have been studied in combination. He omits the critical 4-week titration schedule used in Phase 3 trials. His starting dose (2.5mg) doesn't match clinical trial protocols (2mg). Without medical supervision, purity verification, and proper titration, following this protocol carries unknown risks.
Did he understate the weight loss results?
Yes, significantly. He says "20 to 30 pounds of fat loss in clinical trials" when TRIUMPH-4 actually showed an average of 71.2 lbs (32.3 kg) at the 12mg dose over 68 weeks, and Phase 2 showed up to 58 lbs at 12mg over 48 weeks. Even the lower Phase 2 doses produced more than 30 lbs of weight loss.
Does retatrutide actually preserve muscle?
Miller claims muscle preservation is a key benefit, especially "when paired with high protein intake and strength training." The Phase 2 DXA substudy showed that the ratio of fat loss to lean mass loss was similar to semaglutide and tirzepatide — meaning retatrutide is not uniquely muscle-sparing compared to other GLP-1 drugs. Protein intake and resistance training help preserve lean mass on any weight loss protocol, not specifically because of retatrutide.
Sources
- Miller, G. (2026). "Retrutide or GLP-3 for fat loss and muscle retention!" YouTube. Watch on YouTube
- Jastreboff, A.M., et al. (2023). Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine. DOI: 10.1056/NEJMoa2301972
- Eli Lilly and Company. (2025). TRIUMPH-4 results press release. Press release
- Coskun, T., et al. (2025). Body composition substudy. The Lancet Diabetes & Endocrinology.
Medical Disclaimer
The content on glp3.wiki is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Retatrutide is an investigational drug that has not been approved by the U.S. Food and Drug Administration (FDA) or any other regulatory agency.
Gary Miller's video is not medical advice. He states he is not a doctor. His suggested protocol involves grey market retatrutide and unregulated peptide combinations with no clinical evidence supporting their safety or efficacy when used together.
Do not use this information to make decisions about your health without consulting a qualified healthcare provider. Do not purchase or self-administer grey market peptides based on YouTube videos or any information on this site.
This site is not affiliated with Gary Miller, Gary Miller Fitness, Eli Lilly and Company, or any pharmaceutical manufacturer.
Sources
- Retrutide or GLP-3 for fat loss (YouTube)
YouTube
- Phase 2 trial (NEJM)
New England Journal of Medicine
Related reading
Retatrutide Results: Weight Loss Data and What to Expect
28.7% average weight loss in Phase 3 — here's the full data breakdown by dose, timeline, and what individual results look like.
Retatrutide Dosage & Dosing Guide
How retatrutide is dosed in clinical trials — titration schedule, dose levels, and what each dose achieved.
Does Retatrutide Cause Muscle Loss?
The first DXA body composition data for retatrutide, the glucagon muscle-sparing hypothesis, and evidence-based strategies to preserve lean mass.
Nick Trigili on Retatrutide: His 10-Week Protocol vs What the Data Shows
Trigili's 10-week retatrutide protocol fact-checked against TRIUMPH-4 clinical trial data.