TRT, IGF-1 LR3, and tesamorelin stack: what the science says

What did @jasonposton_ actually say?

Jason says he's using IGF-1 LR3 and tesamorelin alongside TRT, German Volume Training, and 4,500 calories a day, and he's up 10 to 12 pounds. His core claims: IGF-1 LR3 drives faster, bigger muscle and strength gains, while tesamorelin is "an overall better growth hormone secretagog" but produces less dramatic muscle growth. He's upfront that he's eating more and training harder, but insists the compounds are "absolutely beneficial."

That's actually a more honest framing than most peptide content on TikTok. He doesn't claim either compound works in isolation. He doesn't give dosing advice. He acknowledges the results are multifactorial. That matters, and it's worth noting before we get into where the claims get shaky.

Does the science back this up?

Partially, but the picture is more complicated than he makes it sound. IGF-1 LR3 is a synthetic, longer-acting analog of insulin-like growth factor 1. It binds IGF-1 receptors without significant feedback suppression, which is why it's popular in performance circles. The problem is that most of what we know about IGF-1 LR3 comes from animal studies and cell culture, not controlled human trials in healthy athletes.

Tesamorelin has a much stronger evidence base. It's FDA-approved as Egrifta for HIV-associated lipodystrophy, and several randomized controlled trials have confirmed it reduces visceral fat and raises IGF-1 levels. Stanley et al. (2012, Journal of Clinical Endocrinology and Metabolism) showed meaningful reductions in trunk fat in non-HIV adults, though muscle gain was modest and not the primary outcome. Jason's read that tesamorelin is a superior growth hormone secretagog is defensible. His claim that it produces less muscle gain than IGF-1 LR3 is plausible but essentially unverified in head-to-head human data.

What did they get wrong (or right)?

The "very little side effects if any" line is where this gets misleading. IGF-1 LR3 carries real risks that don't get airtime here.

• IGF-1 signaling is linked to cell proliferation. Elevated IGF-1 has been associated with increased risk of colorectal, prostate, and breast cancers in epidemiological studies (Renehan et al., 2004, Lancet). That's not a reason to panic, but it's not a compound to wave off as low-risk.
• Hypoglycemia is a documented and acute risk with IGF-1 analogs. It acts similarly to insulin at high concentrations.
• Tesamorelin side effects include fluid retention, joint pain, and potential glucose dysregulation. The FDA label is explicit about this.

He also doesn't mention that IGF-1 LR3 is not FDA-approved for any indication in humans. It's a research chemical. That's a different regulatory and safety category than tesamorelin, and conflating the two glosses over a real distinction.

What he got right: being transparent about his diet and training context is genuinely uncommon in this space. Attribution matters when you're talking about body composition changes.

What should you actually know?

Here's the practical reality if you're watching this and considering either compound.

Tesamorelin exists as a legitimate, studied pharmaceutical. Its fat-reduction effects are real and documented. But its approved use is specific, and using it off-label for body composition in otherwise healthy people means you're operating outside the clinical trial data. Whether that tradeoff is acceptable is a conversation for you and a licensed physician, not a TikTok comment section.

IGF-1 LR3 is in a different category entirely. It is not approved. It is not compounded legally for human use in the U.S. under current FDA guidelines. Anyone selling it for human injection is operating outside regulatory bounds. The long-term safety profile in healthy humans simply does not exist in peer-reviewed literature.

The 10 to 12 pound gain Jason describes is real to him. But he's also eating 4,500 calories a day, training on a high-volume program, and using TRT. Isolating what any single peptide did in that context is not possible, and he acknowledges that. Give him credit for saying so. Just don't let that honesty obscure the fact that two of the three compounds in his stack carry risks he didn't discuss, and one of them has no legitimate path to legal human use.

If you're working with a physician on peptide therapy, tesamorelin is the only compound in this video with enough clinical data and regulatory standing to have a real informed-consent conversation about. IGF-1 LR3 is not that compound, regardless of how it's framed.