Tesamorelin is a stabilized GHRH(1-44) analogue studied for visceral-fat reduction in HIV 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 does not add growth hormone to the body; it nudges the pituitary gland to release more of its own, in the natural on-off rhythm. That extra growth hormone, working through IGF-1 (a growth signal the liver makes when growth hormone rises), burns off visceral fat (the deep belly fat packed around the organs). In one large HIV trial, that came to a 15.2% drop in visceral fat over six months ^[1]. It is FDA-approved for exactly one use — HIV-associated belly-fat buildup — and nothing else.

Tesamorelin: A Synthetic GHRH Peptide

The tesamorelin peptide is a synthetic 44-amino-acid analogue of human growth hormone-releasing hormone, GHRH(1-44), carrying a trans-3-hexenoic acid group bolted onto its N-terminus ^[7]. That one chemical addition is the whole design idea: it blocks dipeptidyl peptidase-IV (DPP-IV, the enzyme that chops up and switches off natural GHRH within minutes), so the molecule survives long enough to do its job ^[7]. The free base has the empirical formula C221H366N72O67S and a molecular weight near 5,135.9 Da; it is supplied as the acetate salt, catalogued under CAS 218949-48-5, FDA UNII 9MM72X02HA, ATC code H01AC06, and DrugBank ID DB08869.

The "compound" framing matters. This site reads tesamorelin as a chemical entity with a defined structure and a defined evidence base — not as a product. It binds the GHRH receptor on pituitary somatotrophs (the cells that make growth hormone) and triggers the body's own pulsatile (bursting, episodic) growth-hormone release, which is mechanistically different from injecting recombinant growth hormone directly ^[4]. The literature behind it is unusually deep for a peptide of this kind, and unusually well-bounded, which is why every figure on this site is tagged with how strong the evidence behind it actually is.

What the pivotal trials measured

The headline result comes from a 26-week Phase 3 randomized controlled trial of 412 HIV patients with abdominal fat accumulation: tesamorelin 2 mg/day reduced visceral adipose tissue by 15.2%, while placebo increased it by 5.0% ^[1]. In the same trial triglycerides fell by 50 mg/dL (versus a 9 mg/dL rise on placebo) and IGF-1 rose 81.0% ^[1]. A second 52-week program sustained the visceral-fat reduction at -18% versus baseline, with no clinically significant change in glucose parameters over the year ^[2].

The effect is selective. Tesamorelin reduces visceral (intra-abdominal) fat while generally sparing subcutaneous fat and leaving BMI largely unchanged ^[3]. A 2026 meta-analysis pooling five RCTs in HIV-associated lipodystrophy confirmed the pattern: a visceral-fat reduction of -27.71 cm2, a hepatic-fat-fraction drop of -4.28%, and a lean-body-mass gain of +1.42 kg, all at P<0.001, with no serious adverse events reported ^[14]. These are the visceral-fat findings the trials genuinely establish — in the HIV-lipodystrophy population they studied. The full breakdown, with the mechanism and the timeline, is on the research page.

The response is also patterned, not uniform. A pooled analysis of two Phase 3 trials (543 tesamorelin vs 263 placebo) found the odds of dropping visceral fat below 140 cm2 were 3.9-fold greater on tesamorelin (95% CI 2.03-7.44), with baseline metabolic syndrome, triglycerides above 1.7 mmol/L, and white race predicting who responded — and no predictors identifiable as early as 3 months ^[13]. The benefit reaches the quality of the fat as well as the amount: over 26 weeks tesamorelin raised visceral-fat density on CT by +6.2 HU versus placebo (P<0.0001), a marker of healthier adipocytes independent of how much fat was lost ^[12].

Is Tesamorelin FDA Approved?

Yes, but narrowly. Tesamorelin was approved by the FDA in 2010 (NDA 022505) for one indication only: to reduce excess abdominal fat in HIV-infected adults with antiretroviral-related lipodystrophy ^[5]. There is no FDA-approved use outside HIV-associated lipodystrophy. Every other application discussed online — general weight loss, anti-aging, body recomposition, non-HIV fatty-liver treatment, cognitive enhancement — is off-label and investigational, regardless of how mechanistically plausible it sounds.

The distinction this site keeps is precise. Tesamorelin is not "unapproved"; it is an approved prescription drug whose approval covers exactly one population. The material this site discusses is research-grade tesamorelin supplied for laboratory use, which is not the approved finished drug product and carries no purity or potency oversight comparable to it. The NIH LiverTox monograph assigns tesamorelin a likelihood score of E — unlikely to cause clinically apparent liver injury — noting no attributable liver-injury cases in trials ^[5]. Whether the tesamorelin side effects profile and the regulatory scope are acceptable for any given research question is a judgment the literature does not make for you; see the wider set of questions about tesamorelin for how each boundary is framed.

How to read this site

Every finding here carries a confidence grade. ESTABLISHED marks what the pivotal trials genuinely showed in their studied HIV-lipodystrophy population. INVESTIGATIONAL marks the off-label extrapolations — non-HIV fat loss, anti-aging, combination protocols — where the mechanism is plausible but large RCTs are absent. GAP marks the honest unknowns: no large non-HIV fat-loss trial, visceral fat that reaccumulates within weeks of stopping ^[2], and limited long-term oncologic-safety data given that tesamorelin raises IGF-1, a growth factor. The point of grading every claim is that you can see the strength of the evidence at a glance rather than taking a single confident-sounding sentence at face value. Tesamorelin is also prohibited in sport under WADA category S2 ^[15].