Tesamorelin

Tesamorelin is a synthetic 44 amino acid analog of growth hormone releasing hormone, the signal the hypothalamus normally sends to the pituitary gland. Unlike sermorelin and CJC-1295, which are shortened fragments of that hormone, tesamorelin is closer to a full length copy of the natural molecule, engineered with a stabilizing modification so it resists breakdown and lasts longer in circulation. It was developed by Theratechnologies and reached the market in 2010 under the brand name Egrifta after clinical trials in people with HIV. The original medical problem it was built to solve was a specific form of fat redistribution, and its body recomposition following spread out of that clinical setting rather than the other way around. It is sometimes referred to by the research code TH9507.

The reason tesamorelin has a reputation is visceral fat, the deep inflammatory fat packed around the abdominal organs that is more strongly tied to metabolic and cardiovascular risk than the softer fat under the skin. Its approved use is reducing this excess visceral fat in people with HIV-associated lipodystrophy, but off-label interest centers on general body recomposition, anti-aging, and better sleep tied to raising growth hormone naturally. Sources also point to metabolic side benefits seen in trials, including lower triglycerides and improved cholesterol, and some discussion of cognitive and neuroinflammation effects, though that evidence is thinner. In the peptide community it is sometimes stacked with GLP-1 style compounds such as retatrutide, where the idea is that the GLP-1 drives overall weight loss while tesamorelin nudges the loss toward visceral fat, though this pairing is anecdotal rather than trial-backed.

Tesamorelin does not act as growth hormone itself. It mimics growth hormone releasing hormone and prompts the pituitary to put out the body's own growth hormone in natural pulses, which the liver then converts into IGF-1, the downstream messenger that handles fat mobilization and repair. Because it works through the body's own feedback loops rather than flooding the system the way injected growth hormone does, it preserves the pulsatile pattern and tends to carry a gentler side effect profile. What makes its fat effect look selective is biology on the receiving end: visceral fat carries more growth hormone receptors than other fat, so it responds more intently to the growth hormone signal tesamorelin raises. Its full length, stabilized structure is the distinctive engineering detail, giving it a stronger and more durable GHRH signal than the fragment peptides it is usually compared against.

Tesamorelin is given as a subcutaneous injection into the fat layer rather than the muscle, and in trials it was dosed once daily because its half-life is very short, on the order of tens of minutes. That short window is why cadence matters more than with longer-acting compounds: sources describe timing the injection either at night near bedtime or fasted in the morning before exercise, to line up with the body's own largest growth hormone release. Practitioners also flag handling as a common mistake, noting that reconstituted tesamorelin is less forgiving than some peptides, degrades faster, and should be kept cold rather than left sitting at room temperature. It is a systemic signal rather than a local one, so where on the body it is injected is far less important than storage and consistency. None of this should be read as a protocol; it describes how the compound is reported to be used, not a recommendation.

By peptide standards tesamorelin sits on unusually solid ground, because it went through real human randomized trials that measured visceral fat directly with CT scans over roughly 26 weeks at a dose near 2 mg daily, and it earned FDA approval on that basis. That makes it the growth hormone peptide with the strongest clinical proof behind it, and the trials also captured secondary benefits such as reduced triglycerides. The important caveat is that this evidence comes from one specific population, people with HIV-associated fat redistribution, so how well it translates to otherwise healthy adults using it for recomposition or anti-aging is less established. Claims around cognition and broader longevity are more preliminary. Raising growth hormone and IGF-1 also carries theoretical concerns around cancer, and sources consistently treat an active or prior cancer history as a reason for caution.

Tesamorelin is an FDA-approved prescription drug, sold as Egrifta and the later Egrifta SV formulation, approved specifically for reducing excess visceral fat in HIV-associated lipodystrophy. Everything outside that indication, including body recomposition and anti-aging use, is off-label, and much of the material sold in the peptide market comes from compounding pharmacies or research-chemical suppliers rather than the branded product, which affects both cost and quality assurance. It is also expensive relative to other growth hormone peptides. For athletes it is prohibited: growth hormone releasing factors and their analogs, tesamorelin included, sit on the WADA prohibited list at all times, so it is a doping violation in tested sport. As with the whole peptide category, the legal and compounding landscape shifts quickly, and the research code TH9507 is the main alias to recognize.