Coach Colin Watson on Retatrutide: 12-Week Review vs What the Data Shows
Weight loss coach Colin F. Watson published a video titled "Is RETATUTIDE Worth The RISK? NEW GLP-3" sharing his 12-week experience with grey market retatrutide. Watson runs a coaching business and sells peptides through his company J&X Peptides. He describes losing 11 pounds, dropping from 13.8% to 10.9% body fat, and calls retatrutide "probably the most powerful fat loss peptide on the planet."
This page checks his claims and personal observations against published clinical trial data. Watson states the video is for educational purposes only and that he is not telling anyone to use retatrutide.
The Triple Mechanism: Garbled Explanation
Watson explains that retatrutide is called "GLP-3" because "it hits the body in three different ways." He then describes what each receptor does — but mixes up the functions:
"The GIP will basically help to slow down the body's digestive process so you feel full longer... And then you have the GIP. It helps you to take those nutrients and instead of storing them as fat, pull the energy from them... And then the glucagon factor. The glucagon basically helps the blood sugar stay more stable. So you stay in the fat burning zone longer."
| His Description | Actual Receptor Function | Verdict |
|---|---|---|
| GIP slows digestion so you feel full longer | GLP-1 slows gastric emptying and reduces appetite. GIP enhances satiety signals and improves insulin action — it does not slow digestion. | Wrong receptor |
| GIP helps you utilize nutrients instead of storing fat | GIP does improve insulin sensitivity and may reduce fat accumulation, but this oversimplifies a complex metabolic effect. | Partially accurate |
| Glucagon stabilizes blood sugar so you stay in the fat burning zone | Glucagon raises blood sugar by signaling the liver to release glucose. In retatrutide, glucagon receptor activation increases energy expenditure and stimulates fat oxidation directly — not by stabilizing blood sugar. | Misleading |
Watson correctly identifies that retatrutide targets three receptors, but assigns the wrong functions to them. GLP-1 is the receptor that slows digestion — not GIP. And glucagon does not "stabilize" blood sugar; it raises it. The actual metabolic benefit of the glucagon component is increased energy expenditure and direct fat oxidation, not some "fat burning zone" effect.
For the accurate mechanism, see How Retatrutide Works. For why it is called "GLP-3," see GLP-1 vs GLP-3.
"Most Powerful Fat Loss Peptide on the Planet"
Watson calls retatrutide "probably the most powerful fat loss peptide on the planet." Based on available clinical trial data, this claim is largely supported:
| Drug | Max Dose | Weight Loss | Trial Duration |
|---|---|---|---|
| Retatrutide | 12 mg | 28.7% | 68 weeks (TRIUMPH-4) |
| Tirzepatide (Zepbound) | 15 mg | ~22% | 72 weeks (SURMOUNT-1) |
| Semaglutide (Wegovy) | 2.4 mg | ~15–17% | 68 weeks (STEP 1) |
Retatrutide has produced the highest percentage weight loss in any clinical trial to date. However, these are cross-trial comparisons with different patient populations — TRIUMPH-4 enrolled people with obesity and knee osteoarthritis. The ongoing TRIUMPH-5 head-to-head trial against tirzepatide will provide a definitive comparison.
For full trial data, see Retatrutide Results.
His Personal Results
Watson reports losing 11 pounds over 12 weeks on grey market retatrutide, dropping from 13.8% to 10.9% body fat at age 64. He broke down the 11 pounds as roughly 2.5–3 lbs visceral fat, 3.5–4 lbs lean muscle, and the rest body fat. He attributes the lean muscle loss to inadequate protein intake rather than retatrutide itself.
| His Result | Clinical Trial Context | Assessment |
|---|---|---|
| 11 lbs lost in 12 weeks | Phase 2: 12mg group lost ~13 lbs by week 12. Phase 3: ~2 lbs/week average across 68 weeks. | Consistent with low-dose use |
| ~35% of weight loss was lean muscle | Phase 2 DXA substudy: ~26% of weight lost was lean mass. Normal range for any weight loss: 25–40%. | Within expected range |
| Blames muscle loss on low protein intake | Muscle loss occurs with all weight loss regardless of protein intake. Higher protein does help preserve lean mass. | Partially valid — protein matters, but some lean loss is unavoidable |
| Max dose: 5 mg over 12 weeks | Phase 3 titration: 2 → 4 → 6 → 9 → 12 mg (every 4 weeks). 5 mg is below the lowest Phase 3 target dose. | Well below clinical doses |
Watson's results are modest compared to clinical trials, which is expected given his already-lean starting point (13.8% body fat is well below the trial population average of ~40 BMI) and his low maximum dose of 5 mg. His experience is an individual anecdote using grey market product of unknown purity at a sub-clinical dose — not comparable to controlled trial data.
For dosing information, see Retatrutide Dosage.
Muscle Preservation Claim
Watson claims retatrutide is better than other GLP-1 drugs at preserving lean muscle, and says the other drugs cause you to lose "mostly lean muscle and water." Both parts of this claim are wrong.
| Drug | Lean Mass as % of Total Weight Loss | Source |
|---|---|---|
| Retatrutide | ~26% | Phase 2 DXA substudy (Lancet Diabetes & Endocrinology) |
| Tirzepatide | ~26–34% | SURMOUNT-1 DXA substudy |
| Semaglutide | ~39–45% | STEP 1 DXA substudy |
| Normal weight loss (diet/exercise) | 25–40% | Established physiology |
Other GLP-1 drugs do not cause "mostly lean muscle" loss. Even semaglutide, which has the highest lean mass loss ratio, still produces a majority (55–61%) of fat loss. Retatrutide's lean mass ratio (~26%) is comparable to tirzepatide — not dramatically better. The published substudy concluded that retatrutide produces greater total weight loss "without inducing proportionally more loss of lean mass," meaning the ratio is similar, not that it uniquely preserves muscle.
For the body composition data, see Retatrutide and Muscle Loss.
Side Effects: "Not Really Any"
Watson says he and his clients experienced essentially no side effects except appetite suppression: "None of the nausea... the only downside I'm seeing right now is that it's difficult for them to eat."
Clinical trials tell a very different story:
| Side Effect | TRIUMPH-4 (12 mg) | Placebo | Verdict |
|---|---|---|---|
| Nausea | 43.2% | 10.7% | Very common |
| Diarrhea | 33.1% | 13.4% | Common |
| Constipation | 25.0% | 8.7% | Common |
| Vomiting | 20.9% | 0.0% | Common |
| Dysesthesia (skin sensations) | 20.9% | 0.7% | New safety signal |
| Heart rate increase | Up to +6.7 bpm | — | Dose-dependent |
In Phase 3, 43% of participants experienced nausea and 21% experienced vomiting at the 12 mg dose. A novel dysesthesia signal (abnormal skin sensations) emerged in 21% of participants — a safety concern not seen in Phase 2 trials. Watson was using a much lower dose (max 5 mg) of grey market product, which may explain his milder experience, but claiming retatrutide has essentially no side effects is irresponsible and contradicted by extensive clinical data.
For the full safety profile, see Retatrutide Side Effects.
The "Hypothalamic Set Point Reset" Claim
Watson makes perhaps his most speculative claim: that retatrutide can "repair the hypothalamic loop" and help your body "register your body at your new weight set point, making it much easier for you to stick to your new weight." He acknowledges "the jury's not back on it yet."
There is no published evidence supporting this claim for retatrutide or any GLP-1 receptor agonist. In fact, the evidence suggests the opposite:
- STEP 1 extension data: Participants regained two-thirds of their weight loss within one year of stopping semaglutide.
- Tirzepatide discontinuation data: Participants regained an average of 14% of lost weight after stopping.
- Systematic review (eClinicalMedicine): Found significant "metabolic rebound" after GLP-1 drug discontinuation, with hypothalamic signaling downregulating soon after drug cessation.
The weight set point theory is a real scientific concept — the hypothalamus does defend a certain body weight. But the consistent pattern of weight regain across all GLP-1 agonists after discontinuation directly contradicts the idea that these drugs permanently reset the set point.
The Peptide Seller Conflict
Watson discloses that he owns a peptide company called J&X Peptides and links to it throughout the video. He is reviewing a product he sells. This is a significant conflict of interest — he has a direct financial incentive to promote grey market retatrutide.
Grey market retatrutide is unregulated, has no guaranteed purity, and carries risks that pharmaceutical-grade products in clinical trials do not. Watson's experience is with a product of unknown composition at a sub-clinical dose — it may or may not contain what the label claims.
For the risks of grey market peptides, see Grey Market Retatrutide.
Frequently Asked Questions
Who is Coach Colin Watson?
Colin F. Watson describes himself as a weight loss coach who has been "in the fat loss space" for 17 years, helping clients with weight management. He also owns J&X Peptides, a research chemical company that sells grey market retatrutide and other peptides. He is not a physician or medical researcher.
Is his review trustworthy?
Watson's review has several reliability concerns. He sells the product he is reviewing (J&X Peptides), creating a direct financial conflict of interest. He misattributes receptor functions, claims there are essentially no side effects (contradicted by clinical data showing 43% nausea rates), and makes unsupported claims about hypothalamic set point resetting. His personal results are from grey market product of unknown purity at a sub-clinical dose.
Did retatrutide really work for him?
Watson reports losing 11 pounds over 12 weeks on a maximum 5 mg dose, going from 13.8% to 10.9% body fat. These results are plausible but impossible to attribute specifically to retatrutide since he was using grey market product of unknown purity, and similar results could occur with diet and exercise changes alone. Clinical trials used pharmaceutical-grade product at higher doses (up to 12 mg) and showed much greater weight loss (average 71.2 lbs over 68 weeks at 12 mg).
Can you microdose retatrutide like Watson describes?
Watson mentions trying microdosing and says both microdosing and standard dosing gave "relatively similar" fat loss results, with microdosing controlling hunger better. There is no clinical evidence supporting microdosing retatrutide. The Phase 3 trials used specific titration schedules (2 to 4 to 6 to 9 to 12 mg every 4 weeks) to balance efficacy and side effects. Using sub-clinical doses of grey market product tells us nothing about the drug's actual performance. For more, see Microdosing Retatrutide.
Sources
- Watson, C.F. (2025). "Is RETATUTIDE Worth The RISK? NEW GLP-3." 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). Retatrutide body composition substudy. The Lancet Diabetes & Endocrinology.
- Wilding, J.P.H., et al. (2022). Weight regain and cardiometabolic effects after withdrawal of semaglutide. Diabetes, Obesity and Metabolism. DOI: 10.1111/dom.14725
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.
Colin Watson's video is not medical advice. He states the video is for educational purposes only. His review involves grey market retatrutide sold through his own company, creating a direct conflict of interest. His protocol uses sub-clinical doses of unregulated product with no purity verification.
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 Colin F. Watson, J&X Peptides, Eli Lilly and Company, or any pharmaceutical manufacturer.
Sources
- Is RETATUTIDE Worth The RISK? (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.
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.
Retatrutide Side Effects & Safety
Clinical trial safety data, the new dysesthesia signal, and how side effects compare to existing GLP-1 drugs.
Grey Market Retatrutide: Risks, Dangers, and What You Should Know
Grey market retatrutide is unregulated, untested, and potentially dangerous. Here's what the data shows and how to access it safely.