Tesamorelin: GHRH, visceral fat and liver fat

Tesamorelin is a synthetic analogue of growth hormone-releasing hormone (GHRH). Rather than supplying growth hormone directly, it stimulates the pituitary to release the body's own. It is licensed in the United States for a narrow purpose: reducing excess abdominal fat in people with HIV-associated lipodystrophy. This article reviews its pharmacology, the trials behind that use, the research on liver fat, and the limits of what those results show.

This article summarises published research for scientific understanding. It is not treatment or dosing guidance.

The GHRH receptor and the growth hormone axis

GHRH is a hypothalamic peptide that acts on somatotroph cells in the anterior pituitary. It stimulates both their proliferation during development and their production and secretion of growth hormone. Its receptor is a G protein-coupled receptor, expressed predominantly in the pituitary, that signals mainly through cyclic AMP^[1]. Its importance is shown by the little mouse. A mutation in this strain abolishes GHRH binding to the receptor, and the result is severe underdevelopment of somatotroph cells^[1].

Growth hormone released from the pituitary raises insulin-like growth factor 1 (IGF-1), and IGF-1 rose substantially in the tesamorelin trials^[2]. IGF-1 is therefore a useful marker that the axis has been stimulated.

What tesamorelin is

Tesamorelin is a synthetic analogue of human GHRH that stimulates the synthesis and release of endogenous growth hormone^[3]. In the phase 3 trials it is described as GHRH(1-44)^[4], based on the full-length form of the natural hormone. Because it works by stimulating the pituitary, it differs in principle from giving growth hormone itself.

The pivotal trials in HIV

Some people with HIV on antiretroviral therapy accumulate visceral fat, the fat around the abdominal organs, and this is associated with increased cardiovascular risk^[2].

• First phase 3 trial. In 412 people with HIV and abdominal fat accumulation, 26 weeks of daily tesamorelin reduced visceral adipose tissue by 15.2%, compared with a 5.0% increase on placebo. Triglycerides and the ratio of total to HDL cholesterol improved. IGF-1 rose by 81%. There were no significant differences in glycaemic measures^[2].
• Pooled analysis of two phase 3 trials. Across 806 people, visceral fat fell with tesamorelin compared with placebo, a treatment effect of about 15%. Abdominal subcutaneous fat did not change significantly. Triglycerides and measures of belly-related body image also improved. In those who continued tesamorelin to 52 weeks, the reductions were maintained^[4].
• Stopping treatment. When tesamorelin was stopped during the extension phases, visceral fat re-accumulated^[3].

Not everyone responded. Participants whose visceral fat fell by at least 8%, a threshold defined in advance, had greater falls in triglycerides and better preservation of glucose control than non-responders. Changes in lipids and glucose were associated with the degree of visceral fat reduction^[5].

Liver fat and fatty liver disease

Visceral fat is linked to fat accumulation in the liver, and later trials examined this directly in people with HIV.

• Visceral and liver fat. In a randomised trial of 50 people with HIV and abdominal fat accumulation, six months of tesamorelin reduced both visceral fat and liver fat compared with placebo. Fasting glucose rose at two weeks, but the difference over six months was not significant^[7].
• Non-alcoholic fatty liver disease. In a 12-month randomised trial of 61 people with HIV and a liver fat fraction of at least 5%, tesamorelin reduced liver fat by an absolute 4.1 percentage points more than placebo, a relative reduction of 37%. After 12 months, 35% on tesamorelin and 4% on placebo had liver fat below 5%. Fasting glucose and HbA1c did not differ between groups^[8].
• Newer antiretroviral regimens. In a subgroup analysis of participants taking integrase inhibitors, now widely used in HIV treatment, tesamorelin again reduced visceral and liver fat without worsening glucose control^[9].
• Hepatic gene expression. In liver biopsies from the fatty liver trial, tesamorelin shifted gene-expression signatures in directions associated with less fibrosis^[10]. This is a mechanistic finding from one trial. It does not show clinical benefit to the liver.

A 2026 meta-analysis of five randomised trials in HIV found tesamorelin associated with reductions in visceral fat, trunk fat, liver fat and waist circumference, and an increase in lean mass. There was no significant change in subcutaneous fat or body-mass index^[11].

Beyond HIV

Evidence outside HIV is limited. The main study is a 12-month randomised trial of 60 abdominally obese adults without HIV who had relatively reduced growth hormone secretion. Tesamorelin reduced visceral fat, triglycerides and C-reactive protein, and slightly reduced carotid wall thickness, without worsening glucose measures^[6]. This was a specific, selected group, and the trial was small. It does not establish tesamorelin as a treatment for obesity generally.

The HIV results should not be extrapolated to general weight loss. The effect is selective for visceral fat, with little change in subcutaneous fat or body-mass index^[4][11]. The trials measured fat distribution and metabolic markers, not body weight as a primary outcome.

Tesamorelin has also been studied for other outcomes in HIV. In a phase 2 open-label trial of 73 people with HIV, abdominal obesity and neurocognitive impairment, tesamorelin reduced waist circumference. However, the difference in neurocognitive performance between groups was not significant^[12].

Safety reporting

Across the phase 3 programme, serious adverse events occurred in fewer than 4% of participants during 26 weeks. Most of these were injection-site reactions or effects known to be associated with growth hormone, such as joint pain, headache and swelling of the limbs^[3]. The meta-analysis reported arthralgia, myalgia and paraesthesia among associated adverse events^[11]. More participants on tesamorelin than on placebo withdrew because of adverse events in the first phase 3 trial^[2].

Glucose is a recurring question for any treatment that raises growth hormone. In the trials reviewed, overall glycaemic measures were generally not significantly worsened^[2][8]. However, early rises in fasting glucose occurred in one trial^[7], and non-responders showed less favourable glucose changes than responders^[5].

Regulatory context

Tesamorelin was approved in 2010 as the first treatment indicated for reducing excess abdominal fat in HIV-associated lipodystrophy^[3]. A 2024 trial report described it as the only therapy approved by the US Food and Drug Administration for abdominal fat accumulation in people with HIV^[9]. At the time of writing, the Drugs@FDA database listed it as a prescription product under its original 2010 approval. This article makes no claim about its regulatory status in the United Kingdom or elsewhere.

Limitations of the evidence

• Specific population. Most evidence comes from people with HIV on antiretroviral therapy with excess abdominal fat.
• Surrogate outcomes. Trials measured visceral fat, liver fat and blood markers, not cardiovascular events or liver outcomes such as cirrhosis.
• Durability. Visceral fat returned after treatment stopped^[3].
• Variable response. A proportion of participants did not respond^[5].
• Industry links. Several trial authors reported consulting or licensing relationships with the manufacturer^[10][9].

Summary

Tesamorelin is a GHRH analogue that raises endogenous growth hormone and IGF-1. In phase 3 trials in people with HIV, it selectively reduced visceral fat by about 15% and improved triglycerides, with effects that lasted while treatment continued. Later randomised trials showed reductions in liver fat, including in people with HIV and fatty liver disease. Evidence outside HIV is limited to a small trial in obese adults with reduced growth hormone secretion. The findings concern fat distribution in specific populations, not general weight loss, and clinical outcomes beyond these surrogate measures have not been established.