Tesamorelin in bodybuilding and physique optimisation is primarily discussed due to its impact on natural growth hormone (GH) and insulin-like growth factor-1 (IGF-1) pathways. It may support visceral fat reduction, recovery, improved body composition, and metabolic health without the need for direct exogenous human growth hormone (HGH) administration. Unlike recombinant HGH, tesamorelin acts as a synthetic analogue of growth hormone-releasing hormone (GHRH), which stimulates the pituitary gland to increase natural, pulsatile GH secretion [1–3]. For this reason, tesamorelin is often viewed as a more physiological approach for individuals interested in physique recomposition, cutting phases, recovery, and metabolic optimisation.
Tesamorelin works by binding to GHRH receptors on pituitary cells, stimulating the natural release of GH [1,3]. The resulting increase in GH levels then leads to increased production of IGF-1 in the liver and other tissues. IGF-1 is responsible for many of the anabolic and metabolic effects associated with GH signalling, including fat breakdown, protein synthesis, mitochondrial activity, tissue repair, improved recovery, and maintenance of lean muscle mass [4–6]. As tesamorelin stimulates the body’s own GH production rather than directly replacing growth hormone, many consider it to be a more natural way to activate GH-related pathways.
One of the best-documented effects in clinical trials is the reduction of visceral adipose tissue (VAT), i.e. the deep abdominal fat surrounding the internal organs. In a pooled analysis of Phase III trials, Falutz et al. (2010) demonstrated that tesamorelin reduced visceral fat by approximately 15.4% over 26 weeks, whilst improving triglyceride and cholesterol levels [4]. Long-term studies have shown that these reductions could be maintained for up to 52 weeks with continued therapy [5]. Importantly, tesamorelin primarily reduced visceral fat whilst preserving muscle tissue and healthier subcutaneous fat, which is why it is attracting interest in protocols aimed at body composition reduction and recomposition.
Studies have also shown improvements in fatty liver disease and metabolic health. Stanley et al. (2014) reported a significant reduction in both visceral fat and hepatic fat during tesamorelin therapy [6]. Subsequently, Stanley et al. (2019) demonstrated that tesamorelin reduced hepatic fat by approximately 37% relative to baseline values in participants with HIV-associated non-alcoholic fatty liver disease (NAFLD) [7]. These results have increased interest in tesamorelin among bodybuilders and biohackers seeking to improve metabolic health, enhance nutrient utilisation, and gain support during aggressive cutting phases.
Tesamorelin may also improve muscle quality and recovery rather than solely causing rapid muscle gain. Adrian et al. (2019) demonstrated that tesamorelin improved muscle density and increased the cross-sectional area of several trunk muscle groups in participants who achieved visceral fat reduction [8]. Improved muscle density may indicate less intramuscular fat and a healthier muscle structure, which can support performance, recovery, and physique quality.
The tesamorelin-stimulated GH–IGF-1 axis may also improve cellular energy production and regeneration. Makimura et al. (2014) demonstrated that tesamorelin-induced increases in IGF-1 levels were strongly associated with improved mitochondrial function and phosphocreatine regeneration in obese adults with diminished GH secretion [9]. Enhanced mitochondrial efficiency and energy metabolism may support post-exercise recovery, exercise performance, and fatigue resistance.
Tesamorelin is often discussed in the context of body sculpting and recomposition, as its primary clinical effect is the reduction of visceral fat, rather than rapid weight loss. Unlike thermogenics or thyroid-influencing drugs, tesamorelin does not act as a direct fat burner. Instead, it influences hormonal pathways related to GH and IGF-1, gradually impacting fat metabolism, nutrient utilisation, recovery, and body composition [4–7]. Clinical studies have consistently demonstrated improvements in waist circumference, reduction in visceral fat, enhanced lipid profiles, and preservation of muscle tissue rather than just significant decreases in body weight.
Compared to direct HGH injections, tesamorelin may provide more controlled stimulation of GH pathways because it utilises the natural signalling system of the pituitary gland. However, it should be noted that tesamorelin still significantly increases IGF-1 levels, and prolonged stimulation of the GH axis may not be suitable for individuals with active cancers, uncontrolled diabetes, or certain endocrine disorders [1].
The most commonly reported adverse reactions include:
- Reactions at the injection site
- Water retention or mild swelling
- Joint pain or stiffness
- Muscle tension
- Numbness or tingling
- reddening of the skin
- elevated IGF-1 levels [4–6]
Most studies have shown relatively stable fasting glucose and HbA1c levels, however, monitoring remains important as therapies affecting the GH and IGF-1 pathways may impact insulin sensitivity in some individuals [4–7].
Compared to anabolic steroids or suprsyiological use of HGH, tesamorelin appears to be more useful for body recomposition, visceral fat reduction, recovery support, and metabolic optimisation than for extreme muscle hypertrophy or rapid mass building. Current data suggests its strongest effects lie in improving body composition and metabolic health through physiological activation of endogenous GH and IGF-1 signalling.
Disclaimer
This content is for educational and informational purposes only and does not constitute medical, diagnostic or therapeutic advice. Tesamorelin is a prescription medicine approved for specific medical indications and has not been officially approved for bodybuilding or the enhancement of physical performance. Therapies affecting growth hormone and IGF-1 pathways may carry risks, including oedema, glucose metabolism disorders, hormonal disturbances and elevated IGF-1 levels, and should therefore only be used under the supervision of a qualified specialist with appropriate laboratory monitoring. Research-use-only peptides offered by suppliers such as Semax Polska are intended solely for laboratory and scientific research.
References
- 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 from: https://www.ncbi.nlm.nih.gov/books/NBK548730/
- Traynor, K. (2010). FDA approves tesamorelin for HIV-related lipodystrophy. American Journal of Health-System Pharmacy, 67(24), 2082–2082. https://doi.org/10.2146/news100082
- PubChem. (2025). Tesamorelin Compound Summary. National Centre for Biotechnology Information, National Library of Medicine. Available from: https://pubchem.ncbi.nlm.nih.gov/compound/Tesamorelin
- 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
- Falutz, J., Allas, S., Mamputu, J. C., Potvin, D., Kotler, D., Somero, M., Berger, D., Brown, S., Richmond, G., Fessel, J., Turner, R., & Grinspoon, S. (2008). Long-term safety and effects of tesamorelin, a growth hormone-releasing factor analogue, in HIV patients with abdominal fat accumulation. AIDS(14), 1719–1728. https://doi.org/10.1097/QAD.0b013e32830a5058
- Stanley, T. L., Feldpausch, M. N., Oh, J., Branch, K. L., Lee, H., Torriani, M., & Grinspoon, S. K. (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
- Stanley, T. L., Fourman, L. T., Feldpausch, M. N., Purdy, J., Zheng, I., Pan, C. S., Agyapong, G., Torriani, M., Chung, R. T., & Grinspoon, S. K. (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
- Adrian, S., Scherzinger, A., Sanyal, A., et al. (2019). Growth hormone-releasing hormone analogue, tesamorelin, reduces adipose tissue and increases muscle area in adults with HIV. The Journal of Frailty & Ageing, 8(3), 154–159. https://doi.org/10.14283/jfa.2018.45
- Makimura, H., Murphy, C. A., Feldpausch, M. N., & Grinspoon, S. K. (2014). Effects of tesamorelin on phosphocreatine recovery in obese subjects with reduced GH. The Journal of Clinical Endocrinology & Metabolism, 99(1), 338–343. https://doi.org/10.1210/jc.2013-3436