Tesamorelin reduces visceral fat by mimicking the action of growth hormone-releasing hormone (GHRH). This stimulates the pituitary gland to release growth hormone (GH). GH, in turn, influences the liver to produce insulin-like growth factor 1 (IGF-1). Both GH and IGF-1 play a role in lipolysis, the breakdown of fat. Specifically, in the context of visceral fat, tesamorelin has been shown in clinical studies to lead to a significant reduction in visceral adipose tissue in individuals with HIV-associated lipodystrophy.

Tesamorelin reduces visceral fat by increasing the body's natural production of growth hormone (GH) through the activation of growth hormone-releasing hormone (GHRH) receptors in the pituitary gland. As GH levels rise, the body produces more insulin-like growth factor-1 (IGF-1), which helps to increase lipolysis, the process of breaking down stored fat and utilising it for energy. This effect is particularly pronounced in visceral adipose tissue (VAT), which is the deep abdominal fat surrounding internal organs [1–4]. Unlike many weight-loss methods that reduce body weight more generally, tesamorelin primarily focuses on reducing harmful visceral fat while preserving subcutaneous fat and lean muscle mass [2–5].

Visceral fat behaves differently to subcutaneous fat located beneath the skin. It is more metabolically active, more strongly associated with inflammation and metabolic disease, and is more sensitive to growth hormone signalling. Visceral adipose tissue contains a large number of GH-sensitive receptors and exhibits a greater lipolytic response at higher GH and IGF-1 levels. Tesamorelin increases the body’s natural pulsatile release of GH, which activates hormone-sensitive lipase and other enzymes responsible for breaking down triglycerides stored within visceral fat cells [1–4]. The released fatty acids are then used by the body as an energy source, helping to reduce deep abdominal fat stores over time.

Clinical trials in humans have consistently shown that tesamorelin significantly reduces the amount of visceral abdominal fat. In a placebo-controlled trial conducted by Falutz J et al. (2005), HIV-positive adults with abdominal fat accumulation who received tesamorelin experienced a significant reduction in visceral adipose tissue after 12 weeks of treatment [4]. Participants receiving 2 mg daily achieved an approximate 15.71% reduction in visceral fat, along with improved triglyceride levels and an increase in lean body mass, whilst the amount of subcutaneous fat remained relatively stable.

Similar findings were reported by Falutz J et al. (2007), who demonstrated that tesamorelin reduced harmful visceral abdominal fat by approximately 15% over 26 weeks in individuals with HIV-associated lipodystrophy [5]. Lipodystrophy refers to an abnormal redistribution of fat that can occur in some individuals receiving antiretroviral therapy. The study also demonstrated a reduction in waist circumference and an improvement in the lipid profile without any significant deterioration in glucose metabolism. These results suggest that increasing endogenous GH production may selectively reduce metabolically harmful visceral fat deposits.

Long-term phase III clinical trials have confirmed that these effects may persist with continued treatment. In a large, multicentre pooled analysis conducted by Falutz J et al. (2010), tesamorelin reduced visceral fat by approximately 15.4% among 806 HIV-positive participants receiving 2 mg daily [6]. The researchers also observed improvements in waist circumference, waist-to-hip ratio, triglyceride levels and body image. Importantly, participants who discontinued tesamorelin treatment gradually regained visceral fat, suggesting that continued stimulation of GH pathways may be necessary to maintain these benefits.

Research also suggests that tesamorelin may improve the quality and metabolic behaviour of visceral adipose tissue. Stanley TL et al. (2012) demonstrated that participants who achieved at least an 8% reduction in visceral adipose tissue also experienced improvements in triglyceride levels, adiponectin levels and overall markers of metabolic health [7]. Adiponectin is a hormone produced by adipose tissue that supports insulin sensitivity and helps reduce inflammation associated with visceral obesity.

In addition to reducing abdominal fat, tesamorelin also appears to affect fat accumulation in the liver, which is closely linked to visceral obesity and metabolic disorders. Stanley TL et al. (2014) demonstrated that tesamorelin significantly reduced both visceral abdominal fat and liver fat content in HIV-positive individuals with excess abdominal fat [8]. Liver fat refers to fat accumulating within the liver. Similarly, randomised trials on HIV-associated non-alcoholic fatty liver disease (NAFLD) showed that tesamorelin reduced hepatic fat by approximately 37% from baseline, whilst improving the expression of mitochondrial and metabolic genes in the liver [9,10]. Mitochondria are the structures responsible for energy production in cells; therefore, these results may reflect an improvement in cellular energy metabolism.

Certain metabolic factors can affect the strength of the body's response to tesamorelin therapy. Mangili A et al. (2015) demonstrated that individuals with metabolic syndrome, obesity, elevated triglyceride levels, and higher cardiovascular risk markers tended to experience greater visceral fat reduction during treatment [11]. Participants using tesamorelin more frequently lowered visceral fat levels below thresholds associated with increased cardiovascular risk.

The effect of tesamorelin on visceral fat also appears to be consistent regardless of the fat distribution pattern. Rahman F et al. (2023) demonstrated that tesamorelin reduced visceral fat to a similar extent in HIV-positive individuals with and without neck fat accumulation, commonly referred to as a „buffalo hump” [12]. Participants in both groups experienced nearly identical reductions in visceral adipose tissue and waist circumference, suggesting that tesamorelin may effectively reduce deep abdominal fat independent of other fat redistribution patterns.

Generally speaking, tesamorelin reduces visceral fat by stimulating the body's natural production of GH and IGF-1 via physiological GHRH signalling pathways. Increased growth hormone activity enhances the breakdown of fat in metabolically active visceral fat stores, leading to a reduction in visceral fat, improved lipid metabolism, decreased liver fat, and broader metabolic benefits. Clinical studies consistently show that tesamorelin preferentially acts on harmful visceral fat while preserving lean body mass and providing relatively stable glucose control [4–12]. Tesamorelin used in laboratory studies is available from suppliers such as SemaxPolska. It should be noted that research findings relate to controlled scientific conditions and do not constitute confirmation of clinical efficacy in other applications.

Disclaimer

The content is for educational and scientific information purposes only and should not be interpreted as medical advice, diagnosis, or therapeutic recommendation. Tesamorelin is a prescription medication primarily approved for the treatment of HIV-associated lipodystrophy. Therapies affecting growth hormone and metabolic pathways require medical supervision, laboratory monitoring, and individual clinical assessment by a qualified healthcare professional.

References

1. LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. (2018). Tesamorelin. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases. Available at: NCBI Bookshelf: Tesamorelin – An Overview
2. PubChem. (2025). Tesamorelin Compound Summary. National Centre for Biotechnology Information. Available at: PubChem: Tesamorelin Summary
3. Stanley TL, Chen, C. Y., Branch, K. L., et al. (2011). Effects of a growth hormone-releasing hormone analogue on endogenous GH pulsatility and insulin sensitivity in healthy men. The Journal of Clinical Endocrinology & Metabolism, 96(1), 150–158. https://doi.org/10.1210/jc.2010-1586
4. Falutz J, Allas, S., Kotler, D., et al. (2005). Placebo-controlled dose-ranging study of a growth hormone-releasing factor in HIV-infected patients with abdominal fat accumulation. AIDS, 19(12), 1279–1287. https://doi.org/10.1097/01.aids.0000180099.35146.30
5. Falutz J, Allas, S., Blot, K., et al. (2007). Metabolic effects of a growth hormone-releasing factor in patients with HIV. The New England Journal of Medicine, 357(23), 2359–2370. https://doi.org/10.1056/NEJMoa072375
6. Falutz J, Mamputu, J. C., Potvin, D., Moyle, G., Soulban, G., Loughrey, H., Marsolais, C., Turner, R., & Grinspoon, S. (2010). Effects of tesamorelin (TH9507), a growth hormone-releasing factor analogue, in human immunodeficiency virus-infected patients with excess abdominal fat: A pooled analysis of two multicentre, double-blind placebo-controlled phase 3 trials with safety extension data. The Journal of Clinical Endocrinology & Metabolism, 95(9), 4291–4304. https://doi.org/10.1210/jc.2010-0490
7. Stanley TL, Falutz, J., Marsolais, C., et al. (2012). Reduction in visceral adiposity is associated with an improved metabolic profile in HIV-infected patients receiving tesamorelin. Clinical Infectious Diseases, 54(11), 1642–1651. https://doi.org/10.1093/cid/cis251
8. Stanley TL, Feldpausch, M. N., Oh, J., et al. (2014). Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation: A randomised clinical trial. JAMA, 312(4), 380–389. https://doi.org/10.1001/jama.2014.8334
9. Fourman LT, Billingsley, J. M., Agyapong, G., Ho Sui, S. J., Feldpausch, M. N., Purdy, J., Zheng, I., Pan, C. S., Corey, K. E., Torriani, M., Kleiner, D. E., Hadigan, C. M., Stanley, T. L., Chung, R. T., & Grinspoon, S. K. (2020). Effects of tesamorelin on hepatic transcriptomic signatures in HIV-associated NAFLD. JCI Insight, 5(16), e140134. https://doi.org/10.1172/jci.insight.140134
10. Stanley TL, Fourman, L. T., Feldpausch, M. N., et al. (2019). Effect of tesamorelin on non-alcoholic fatty liver disease in HIV-positive individuals: A randomised, double-blind, multicentre study. The Lancet HIV, 6(12), e821–e830. https://doi.org/10.1016/S2352-3018(19)30338-8
11. Mangili A, Falutz, J., Mamputu, J. C., Stepanians, M., & Hayward, B. (2015). Predictors of treatment response to tesamorelin, a growth hormone-releasing factor analogue, in HIV-infected patients with excess abdominal fat. PLoS ONE, 10(10), e0140358. https://doi.org/10.1371/journal.pone.0140358
12. Rahman F, McLaughlin, T., Mesquita, P., Morin, J., Potvin, D., De Chantal, M., & Aberg, J. A. (2023). Effect of tesamorelin in people with HIV with and without dorsocervical fat: Post hoc analysis of phase III double-blind placebo-controlled trial. Journal of Clinical and Translational Science, 7(1), e40. https://doi.org/10.1017/cts.2022.515