Tesamorelin: An Approved Peptide With a Narrow Indication

The short version

Tesamorelin is a synthetic 44-amino-acid analogue of human growth hormone-releasing hormone (GHRH), the signal the hypothalamus sends to the pituitary to release growth hormone. By mimicking that signal, tesamorelin causes the body's own pituitary to secrete more GH, which in turn drives the liver to produce IGF-1 — and together those two hormones preferentially mobilize visceral (deep abdominal) fat.

Unlike the other two peptides on this desk, tesamorelin is FDA-approved. But the approval is specific: it was granted in 2010 for reducing excess abdominal fat in adults with HIV-associated lipodystrophy — the fat redistribution caused by antiretroviral therapy ^[9]. A 2026 meta-analysis of five RCTs confirmed visceral fat reduction (mean -27.71 cm2), hepatic fat reduction (-4.28%), and lean-mass gain (+1.42 kg) in that population ^[8]. Outside HIV lipodystrophy, all use is off-label and investigational.

Tesamorelin is banned in sport (WADA S2 category). Visceral fat reaccumulates within weeks of discontinuation. This page describes the clinical literature; it gives no dose and no advice.

What it is

Tesamorelin is a 44-amino-acid synthetic analogue of human GHRH(1-44), with one modification: a trans-3-hexenoic acid group conjugated to the N-terminus. That single structural change makes tesamorelin resistant to cleavage by dipeptidyl peptidase-IV (DPP-IV), the enzyme that rapidly degrades native GHRH in the bloodstream, extending plasma stability and making daily dosing clinically practical.

Its formal drug name reflects its derivation from the growth hormone-releasing factor (GRF) framework. It is also known by its development code TH9507, and synonyms GHRH(1-44) analogue and trans-3-hexenoyl-GHRH(1-44) amide appear in the literature. The molecular formula of the free base is C221H366N72O67S. It is supplied clinically as the acetate salt and is administered by subcutaneous injection.

How it works

Tesamorelin binds the GHRH receptor (GHRH-R) on somatotroph cells in the anterior pituitary. Receptor binding activates the Gs-protein/adenylyl cyclase/cAMP/PKA cascade inside those cells, which stimulates synthesis and pulsatile secretion of endogenous growth hormone. The GH released enters the circulation and drives the liver to produce IGF-1.

Both GH and IGF-1 then act on visceral adipose tissue to promote lipolysis — the breakdown of stored triglycerides for energy. Because tesamorelin amplifies the body's own pulsatile GH rhythm rather than supplying exogenous GH directly, its metabolic profile differs from recombinant GH: the pulsatility is preserved, the feedback axis remains intact, and the IGF-1 rise is more physiological in character ^[11]. In healthy men given tesamorelin 2 mg/day for two weeks, mean overnight GH increased (+0.5 ug/L, P=0.004) and IGF-1 rose by 181 ug/L (P<0.0001), without significant changes in fasting glucose or insulin sensitivity ^[11].

What the research shows

Meta-analysis of five RCTs in HIV lipodystrophy. A 2026 pooled analysis of the trial program found tesamorelin produced statistically significant reductions in visceral adipose tissue (mean -27.71 cm2, 95% CI -38.37 to -17.06; P<0.001), trunk fat (mean -1.18 kg), and hepatic fat fraction (mean -4.28%), alongside an increase in lean body mass (mean +1.42 kg) — all without serious adverse events in the pooled safety data ^[8].

JAMA RCT — visceral and hepatic fat. In 50 antiretroviral-treated HIV adults, tesamorelin 2 mg/day for 6 months 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) ^[10]. The hepatic finding is notable because fatty liver is a recognized complication of antiretroviral therapy.

52-week sustained efficacy. In the pivotal program (tesamorelin 2 mg/day, n=273), visceral fat reduction was sustained at approximately -18% over 52 weeks (P<0.001 vs. baseline). Critically, visceral fat reaccumulated upon discontinuation, and glucose parameters over 52 weeks were not clinically significantly different from placebo ^[12].

GH pulsatility and insulin sensitivity (healthy men). Tesamorelin increased GH and IGF-1 without affecting fasting glucose (P=0.93) or insulin-stimulated glucose uptake (P=0.61) over two weeks in 13 healthy men, supporting the physiological pulsatility argument ^[11].

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

Reported effects, cautions & safety

No community-anecdote reports are compiled in this desk's source material for tesamorelin, so none are presented. The following cautions come from the cited clinical literature and regulatory record.

• Narrow approved indication. FDA approval is limited to HIV-associated lipodystrophy ^[9]. General visceral-fat reduction, anti-aging, cognitive enhancement, and non-HIV fatty liver are off-label, investigational uses without large-RCT support.
• Pivotal trials in a specific population. All efficacy data come from HIV-positive adults on antiretroviral therapy. Generalizability to non-HIV populations is mechanistically plausible but not established by equivalent controlled trials.
• Effect contingent on continued dosing. Visceral fat reaccumulates within weeks of stopping tesamorelin ^[12]. Benefits are not durable off-treatment.
• IGF-1 elevation and oncologic uncertainty. Tesamorelin stimulates GH-axis activity and raises IGF-1, a growth factor. Trials showed no excess malignancy signal over 52 weeks, but long-term oncologic safety data are limited. Active malignancy is a labeled contraindication.
• Glucose perturbation. Modest glucose changes can occur, warranting monitoring in individuals with prediabetes or dysglycemia — though the dedicated type-2-diabetes cohort analysis found no significant HbA1c change.
• WADA prohibition. Tesamorelin is prohibited in sport under the WADA Prohibited List, category S2 (peptide hormones, growth factors, related substances and mimetics), in- and out-of-competition. Athlete use carries sanctions.
• Research-grade supply limitations. High pharmaceutical cost and injection-only administration limit access to the approved product; research-grade material lacks the purity and potency oversight of the clinical formulation.

Where it fits in metabolic research

Tesamorelin occupies the middle ground on this desk: it has more human evidence than MOTS-c, and it is actually approved rather than investigational like retatrutide — but its approval is tightly scoped. It is the only peptide here that works through the growth hormone axis rather than direct metabolic-receptor signaling, and it is the only one with a clear hepatic-fat reduction signal alongside visceral-fat data. Its fundamental practical constraint is the rebound: the effect is real, but it stops when the peptide stops. See the comparison page for the full side-by-side.