Investigational · not FDA approved

Editorially reviewed · Last updated February 2026 · How we review

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

How we keep this honest

What this is: Educational information, not medical advice. It reports published research — it doesn’t recommend that you use, obtain, or supply anything.
Regulatory status: Retatrutide and similar peptides are investigational — not approved by the FDA or any regulator. Semaglutide and tirzepatide are prescription-only medicines, available only through a licensed prescriber.
Our standard: Every claim traces to a primary source. We label the strength of evidence and flag estimates as estimates — never as clinical fact.
No commercial ties: We don’t sell, supply, or link to suppliers of any medicine, and aren’t affiliated with any manufacturer.

Do not make decisions about your health without consulting a qualified healthcare provider. For trial enrolment, see ClinicalTrials.gov. More on how we review.

Sources

Is RETATUTIDE Worth The RISK? (YouTube)
YouTube
Phase 2 trial (NEJM)
New England Journal of Medicine

Grounded in primary sources

NEJM

The Lancet

JAMA

FDA

ClinicalTrials.gov

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