Tesamorelin: The Desk's One Regulated Compound

The short version

Tesamorelin is a synthetic 44-amino-acid analogue of human growth hormone-releasing hormone (GHRH), bearing a chemical modification — a trans-3-hexenoic acid group at the N-terminus — that makes it resistant to the enzyme that normally degrades GHRH quickly in the bloodstream. It stimulates the pituitary gland to release growth hormone in a more physiological pulsatile pattern rather than flooding the body with exogenous GH ^[12].

It is the only peptide on this desk with an FDA approval: NDA 022505 was granted in November 2010 to reduce excess abdominal fat in HIV-infected adults with antiretroviral-related lipodystrophy ^[9]. In that specific population, randomized controlled trials show a sustained reduction in visceral adipose tissue (VAT) of roughly 18% over 52 weeks ^[12] and a treatment effect of -42 cm2 in visceral fat versus placebo in a JAMA trial ^[10]. Outside that indication — general visceral-fat reduction, anti-aging, body recomposition — all use is off-label and the evidence is markedly weaker.

Tesamorelin is prohibited in sport under WADA S2. Research-grade material sold outside a prescription context is not approved for human self-administration.

What it is

Tesamorelin (also known as TH9507) is a synthetic analogue of human GHRH(1-44)-NH2 — the 44-amino-acid C-terminal amide form of endogenous growth hormone-releasing hormone. Its defining structural feature is an N-terminal trans-3-hexenoic acid conjugation that confers resistance to cleavage by dipeptidyl peptidase-IV (DPP-IV), extending plasma stability relative to native GHRH.

The free-base empirical formula is C221H366N72O67S; it is supplied clinically as the acetate salt. Synonyms include Trans-3-hexenoyl-GHRH(1-44) amide and GHRH(1-44) analogue. Unlike AOD-9604, which does not bind the growth hormone receptor at all, tesamorelin works one step upstream — through the pituitary — to encourage the body's own GH axis.

How it works

Tesamorelin binds the growth hormone-releasing hormone receptor (GHRH-R) on anterior-pituitary somatotroph cells. This activates the Gs/adenylyl-cyclase/cAMP/PKA cascade, stimulating synthesis and pulsatile secretion of endogenous growth hormone. The resulting GH drives hepatic production of insulin-like growth factor-1 (IGF-1), and together GH and IGF-1 promote lipolysis preferentially in visceral adipose tissue.

Because tesamorelin amplifies the body's own pulsatile GH rhythm rather than supplying exogenous GH, its metabolic profile differs from recombinant human growth hormone. A 2-week study in 13 healthy men confirmed meaningful increases in both overnight GH pulsatility and IGF-1, without significant changes in fasting glucose or insulin-stimulated glucose uptake — insulin sensitivity was preserved at least over that short window ^[11].

What the research shows

52-week RCT programme. The pivotal study (tesamorelin 2 mg/day, n=273, vs placebo n=137 in HIV-infected adults) found that VAT reduction was sustained at -18% over 52 weeks (P<0.001 vs baseline). Visceral fat reaccumulated on discontinuation, and changes in glucose parameters over 52 weeks were not clinically significant ^[12].

JAMA visceral fat and liver fat trial. A 6-month RCT in 50 antiretroviral-treated HIV adults produced a treatment effect of -42 cm2 in visceral fat (P=0.005) and reduced hepatic lipid-to-water percentage by a net -2.9% (P=0.003). The liver-fat signal is notable given the hepatic-fat burden common in this population ^[10].

2026 meta-analysis. A pooled analysis of five RCTs in HIV-associated lipodystrophy found tesamorelin reduced VAT by a mean of -27.71 cm2 (95% CI -38.37 to -17.06; P<0.001), trunk fat by -1.18 kg, and hepatic fat fraction by -4.28%, while increasing lean body mass by +1.42 kg, all P<0.001, with no serious adverse events ^[8].

GH pulsatility and insulin sensitivity in healthy men. Two weeks of tesamorelin 2 mg/day in 13 healthy non-HIV men raised mean overnight GH by 0.5 ug/L (P=0.004) and IGF-1 by 181 ug/L (P<0.0001); insulin-stimulated glucose uptake was not significantly affected (P=0.61) ^[11].

Hepatic safety. The NIH LiverTox monograph assigns tesamorelin a likelihood score of E — unlikely to cause clinically apparent liver injury — noting no reported attributable liver-injury cases and no de novo serum-enzyme elevations in trials ^[9].

Reported effects, cautions & safety

Tesamorelin's controversy profile in the literature is clearer than its clinical trial record:

Cited cautions from the literature

• FDA approval is limited to HIV-associated lipodystrophy. All other uses — general visceral-fat reduction, anti-aging, cognitive enhancement, non-HIV NAFLD — are off-label and investigational.
• Pivotal efficacy trials were conducted exclusively in HIV-positive adults on antiretroviral therapy; generalizability to non-HIV populations is mechanistically plausible but not established by large RCTs.
• Visceral fat reaccumulates within weeks of discontinuation ^[12]; benefits are contingent on continued dosing.
• GH-axis stimulation raises serum IGF-1; while trials showed no excess malignancy signal over 52 weeks, long-term oncologic-safety data are limited, and active malignancy is a labeled contraindication.
• Modest glucose perturbation can occur; monitoring is warranted in individuals with prediabetes or dysglycemia.
• Tesamorelin is prohibited in sport under the WADA Prohibited List (S2: peptide hormones, growth factors, related substances and mimetics), in- and out-of-competition.
• High pharmaceutical cost and injection-only administration limit access; research-grade material lacks the purity and potency oversight of the approved prescription product.

No community-anecdote reports are compiled in this desk's source material for tesamorelin; the cautions above are drawn from the cited literature.

Where it fits in metabolic research

Tesamorelin is the bridge compound on this desk. Where AOD-9604 represents a direct lipolytic fragment that failed human translation, tesamorelin represents a hormonal-relay approach that succeeded in a narrow indication ^[9]. Where MOTS-c is entirely preclinical, tesamorelin has a published human RCT body of work going back to 2008. Its limitation is specificity: the indication is HIV lipodystrophy, the evidence base is that population, and extrapolation to general metabolic use is unsupported by controlled human data. It shows what a peptide acting on the GH axis can achieve when the patient population and outcome are well-matched. See the comparison page for how all three line up.