Tesamorelin is a GHRH analogue studied to reduce visceral abdominal fat in HIV-associated lipodystrophy.

The short version

Tesamorelin is a lab-made copy of GHRH (the brain's own "make growth hormone" signal), built to last longer in the blood than the natural version. It tells the pituitary to release the body's own growth hormone, which then raises IGF-1 (a growth signal the liver makes when growth hormone goes up). Together those break down deep belly fat. In studies of people living with HIV who had abnormal fat buildup, 2 mg a day cut visceral fat (the deep fat packed around the organs) by about 15% in six months ^[1]. The U.S. FDA approved it for that one HIV-related use in 2010 ^[5]. Every other use — general weight loss, anti-aging, performance — is off-label and not approved. This page is a plain reading of the published record, not a how-to or a place to buy anything.

What the tesamorelin record actually shows

Tesamorelin is a synthetic 44-amino-acid analogue of human growth hormone-releasing hormone, GHRH(1-44), carrying a trans-3-hexenoic acid group on its N-terminus that blocks the enzyme DPP-IV (dipeptidyl peptidase-IV, the protease that rapidly chews up natural GHRH). That single modification is the whole design: it lets the molecule survive long enough to act, so it stimulates the body's own pulsatile growth hormone (GH) rather than replacing it. Native GHRH is cleared so fast it makes a poor drug; tesamorelin's stabilized N-terminus is the engineering answer to that problem.

The efficacy record is built on two pivotal Phase 3 trials in HIV-associated lipodystrophy. In the first, 412 HIV patients with abdominal fat accumulation received tesamorelin 2 mg subcutaneously once daily; over 26 weeks visceral adipose tissue fell 15.2% while placebo rose 5.0%, triglycerides dropped 50 mg/dL, and IGF-1 rose 81.0% ^[1]. The 52-week program sustained the visceral-fat reduction at about -18% versus baseline, and the fat reaccumulated when dosing stopped ^[2]. A 2026 meta-analysis pooling five randomized controlled trials reported visceral adipose tissue -27.71 cm2 versus control, with hepatic fat fraction -4.28% and lean body mass +1.42 kg, no serious adverse events ^[3].

The reduction is selective. Tesamorelin lowers the deep visceral fat packed around the organs while generally leaving subcutaneous fat and overall BMI unchanged — the studied effect is a fat-distribution shift, not broad weight loss. A pooled analysis of two Phase 3 trials found the odds of bringing visceral fat below 140 cm2 were 3.9-fold higher with tesamorelin than placebo (95% CI 2.03-7.44) ^[13], and the metabolic benefit tracked the degree of fat lost rather than the dose alone ^[11].

Those are HIV-population research findings, not promises. See the visceral-fat trial results for the full table, and the full reference list for every source.

Tesamorelin Peptide: A Research Classification

Classified plainly, the tesamorelin peptide is a peptide hormone — a chain of 44 amino acids that acts as a growth hormone-releasing hormone receptor agonist (a key that fits the GHRH receptor lock). It is not growth hormone itself and not a small-molecule drug; it is a stabilized analogue of a hypothalamic peptide the body already makes. Its molecular weight is 5135.9 Da and it is supplied as the acetate salt (CAS 218949-48-5) ^[5].

The "peptide" framing matters because it sets the mechanism apart from recombinant GH: tesamorelin amplifies the body's existing pulsatile GH rhythm at the pituitary rather than flooding the bloodstream with a continuous external hormone. In a mechanistic study of 13 healthy men, 2 mg/day for two weeks raised mean overnight GH by 0.5 ug/L and IGF-1 by 181 ug/L ^[4]. Research-grade material described as tesamorelin peptide and sold for laboratory use is not the approved finished drug product and lacks its purity and potency oversight.

What Is Tesamorelin Used For

Tesamorelin has one approved use and several investigational ones, and the distinction is the most important fact on this page.

The approved indication is narrow: reducing excess abdominal fat in HIV-infected adults with antiretroviral-related lipodystrophy (a fat-redistribution complication of HIV and its treatment) ^[5]. That is the only use the FDA has cleared, and it is why the entire efficacy dataset comes from HIV-positive adults on antiretroviral therapy.

The investigational and off-label research areas include hepatic fat. In a 6-month JAMA trial of 50 antiretroviral-treated HIV adults, tesamorelin produced a visceral-fat treatment effect of -42 cm2 and reduced liver lipid-to-water percentage by a net -2.9% ^[6]. Cognition has also been studied, with mixed results. None of these extends the approval: NAFLD/MASLD use, general or cosmetic fat loss, anti-aging, and performance use are all off-label and not FDA-approved. The pivotal efficacy data sit entirely inside the HIV population ^[1].

This matters for anyone reading about tesamorelin as a general fat-loss agent. The mechanism is the same regardless of who receives it — stimulate GH, raise IGF-1, drive visceral lipolysis — so non-HIV use is mechanistically plausible. But "plausible" is not "established": no large general-population fat-loss RCT has been completed, so the off-label evidence is mechanistic and small-study, not pivotal. This site keeps those two categories visibly apart.

Is Tesamorelin a Steroid?

No. Tesamorelin is a peptide hormone — specifically a GHRH analogue — not an anabolic steroid. Steroids are lipid-based molecules built on a four-ring carbon skeleton; tesamorelin is a 44-amino-acid chain. The mechanisms differ at the root: an anabolic steroid supplies an exogenous hormone directly, while tesamorelin supplies no hormone at all. It instead signals the pituitary to release the body's own growth hormone in its natural pulsatile rhythm, which then raises IGF-1 ^[4]. For sport, that distinction does not change its status: tesamorelin is prohibited under the WADA Prohibited List category S2 (peptide hormones, growth factors, related substances and mimetics), in- and out-of-competition.