Tesamorelin vs HGH: How They Differ

Tesamorelin is a 44-amino-acid analogue of growth hormone releasing hormone (GHRH) that signals the pituitary to release the body’s own growth hormone, while HGH (somatropin) is growth hormone itself, a 191-amino-acid protein that acts directly on growth hormone receptors. One works one step upstream and keeps the pituitary in the loop; the other bypasses it. Both have been tested in the same population, adults with HIV and excess abdominal fat, which makes this one of the cleaner comparisons in the growth hormone literature. Here is how they differ and what the human trials found.

Findings

• Tesamorelin raises growth hormone through the pituitary. In 13 healthy men, two weeks of tesamorelin increased mean overnight growth hormone, pulse size and basal secretion, with insulin-stimulated glucose uptake unchanged (2011).
• In a 26-week trial of 412 adults with HIV and abdominal fat, visceral fat fell 15.2% on tesamorelin and rose 5.0% on placebo, and IGF-1 rose 81% (2007).
• HGH is identical in sequence to pituitary growth hormone and is an approved medicine for growth hormone deficiency in children and adults.
• In 325 adults with HIV-associated fat redistribution, 12 weeks of HGH cut visceral fat by 32.6 cm² against 0.5 cm² on placebo (2007).

What is tesamorelin?

Tesamorelin is a synthetic analogue of human GHRH, the hypothalamic hormone that tells the pituitary to make growth hormone. It carries the full 44-amino-acid GHRH(1-44) sequence (Falutz et al., J Clin Endocrinol Metab, 2010), with one modification at its N-terminus described in Tesamorelin: One Small Change to a Natural Hormone. Because it acts at the pituitary GHRH receptor, the growth hormone it produces is the body’s own, released by the gland’s normal machinery.

That point was tested directly in 13 healthy men given tesamorelin once daily for two weeks, with frequent overnight blood sampling. Mean overnight growth hormone, the area of each growth hormone peak and basal secretion all rose, IGF-1 climbed by 181 µg/L, and neither fasting glucose nor insulin-stimulated glucose uptake changed significantly (Stanley et al., J Clin Endocrinol Metab, 2011). In other words, the pulses got bigger rather than being replaced by a flat level.

A prescription formulation of tesamorelin was approved by the US FDA in November 2010 to reduce excess abdominal fat in adults with HIV-associated lipodystrophy, and Health Canada has also authorised it for excess visceral fat in the same population.

The visceral-fat trials

The pivotal 2007 trial randomised 412 adults with HIV and abdominal fat accumulation to daily subcutaneous tesamorelin or placebo for 26 weeks. Visceral fat measured by CT fell 15.2% with tesamorelin and rose 5.0% with placebo. Triglycerides fell by 50 mg/dL against a 9 mg/dL rise, the total-to-HDL cholesterol ratio improved, IGF-1 rose 81%, and glycaemic measures did not differ between groups (Falutz et al., N Engl J Med, 2007).

A pooled analysis of two phase 3 trials (806 patients) put the treatment effect on visceral fat at 15.4% at 26 weeks, with abdominal subcutaneous fat essentially unchanged. Patients who stayed on tesamorelin to 52 weeks kept the reduction, at 17.5% below baseline, along with lower triglycerides and a smaller waist (Falutz et al., J Clin Endocrinol Metab, 2010). A 2014 trial of 50 patients added liver fat, which fell by a net 2.9 percentage points in lipid-to-water ratio over six months (Stanley et al., JAMA). The full record is in Tesamorelin and Visceral Fat: The Trial Record and Tesamorelin and Liver Fat.

What is HGH?

HGH, or recombinant human growth hormone (somatropin), is a single-chain protein of 191 amino acids with two internal disulfide bonds. It is made in bacteria, and its primary and secondary structure is identical to growth hormone from the human pituitary. Canadian product monographs list it for growth failure from growth hormone inadequacy, chronic renal insufficiency and Turner syndrome in children, and for replacement in adults with confirmed growth hormone deficiency (Canadian somatropin product monograph, 2012). It acts on growth hormone receptors in the liver and other tissues directly, so the pituitary is not involved.

HGH in the same population

HGH was trialled in adults with HIV and excess trunk fat before tesamorelin. In a 2007 trial of 325 patients, 12 weeks of daily HGH reduced visceral fat by 32.6 cm² against a 0.5 cm² rise on placebo and lowered non-HDL cholesterol; patients continuing on a reduced alternate-day schedule held their visceral and trunk fat losses to week 36, with limb fat also falling (Grunfeld et al., J Acquir Immune Defic Syndr, 2007).

A smaller design asked whether low, physiological replacement would do the same. Fifty-six patients with HIV, abdominal fat and reduced growth hormone secretion received HGH titrated to the upper quarter of the normal IGF-1 range, or placebo, for 18 months. Visceral fat fell by 19 cm² relative to placebo, with lower trunk fat, diastolic blood pressure and triglycerides; 2-hour glucose on a tolerance test rose by 22 mg/dL (Lo et al., JAMA, 2008).

HGH in healthy older adults

The best-known HGH study outside deficiency states gave 12 healthy men aged 61 to 81 growth hormone for six months: lean body mass rose 8.8% and fat mass fell 14.4% (Rudman et al., N Engl J Med, 1990). A 2007 systematic review of 220 treated participants across 18 study populations found fat mass down 2.1 kg and lean mass up 2.1 kg, with more soft-tissue swelling, joint pain and carpal tunnel syndrome, and noted that anti-ageing use is not an approved indication in the United States (Liu et al., Ann Intern Med, 2007).

How do tesamorelin and HGH compare side by side?

Question	Tesamorelin	HGH (somatropin)
What is it?	Synthetic GHRH analogue	Recombinant growth hormone
Size	44 amino acids	191 amino acids
Where it acts	Pituitary GHRH receptor	Growth hormone receptors in tissues
Growth hormone pattern	Larger natural pulses and basal secretion	Set by the administered amount
Main research area	Visceral and liver fat in HIV	Growth hormone deficiency, body composition
Human evidence	Phase 3 trials, 806 patients pooled	Decades of approved clinical use and trials
Forms we supply	10 mg lyophilised vial	Not supplied

Why does the mechanism difference matter for research?

• The pituitary stays in the loop with tesamorelin. Because it works through the gland, output depends on the pituitary’s own capacity, and the 2011 sampling study showed it arrives as enlarged pulses.
• HGH gives a fixed, known exposure. For questions about growth hormone itself, independent of pituitary capacity, the hormone is the direct variable; it is also the only option where the pituitary cannot respond, as in deficiency.
• The fat-distribution signal differs. Tesamorelin’s pooled data showed visceral fat falling while abdominal subcutaneous fat held steady; the 2007 HGH trial also reported limb-fat loss.

No randomised trial was found that compared the two head to head, so differences in size of effect across separate trials reflect different doses, durations and populations rather than a direct contest. Tesamorelin is compared with other growth hormone secretagogues in CJC-1295 + Ipamorelin vs Tesamorelin and with HGH from the secretagogue side in CJC-1295 + Ipamorelin vs HGH.

How is tesamorelin supplied?

Vistara Labs supplies tesamorelin as a 10 mg lyophilised vial, and in the Tesamorelin + Ipamorelin Stack. It is reconstituted with bacteriostatic water (see the tesamorelin reconstitution guide) and lasts only about a week once mixed, as covered in how long tesamorelin lasts. Certificates of analysis are on the lab reports page, buying details are in Tesamorelin in Canada, and every order ships from within Canada. Vistara Labs does not supply HGH.

Frequently asked questions

Is tesamorelin the same as HGH?

No. Tesamorelin is a 44-amino-acid analogue of growth hormone releasing hormone that prompts the pituitary to release its own growth hormone. HGH is the 191-amino-acid growth hormone protein itself and acts on tissues directly.

Is tesamorelin stronger than HGH?

They have not been compared head to head in a randomised trial, so there is no direct answer. In separate trials in adults with HIV and abdominal fat, tesamorelin reduced visceral fat by 15.2% over 26 weeks and HGH by 32.6 cm² over 12 weeks, in different patients, doses and designs.

Does tesamorelin raise IGF-1?

Yes. IGF-1 rose 81% on tesamorelin in the 412-patient 2007 trial, and by 181 µg/L after two weeks in a 2011 study of healthy men, where growth hormone pulses also grew larger.

Can tesamorelin and HGH be studied together?

No published human research on the combination was found. Both raise IGF-1, so in one design their effects would overlap and be hard to separate; the published trials studied each on its own.

Where can I buy tesamorelin in Canada?

Vistara Labs supplies tesamorelin as a 10 mg lyophilised vial for laboratory research, with certificates of analysis online, shipped from within Canada by Canada Post Xpresspost.

Product details from vistaralabs.ca, October 2026. Sources: Falutz J et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. N Engl J Med. 2007. PMID 18057338. Falutz J et al. Effects of tesamorelin (TH9507), a growth hormone-releasing factor analog, in human immunodeficiency virus-infected patients with excess abdominal fat: a pooled analysis of two multicenter, double-blind placebo-controlled phase 3 trials with safety extension data. J Clin Endocrinol Metab. 2010. PMID 20554713. Stanley TL et al. Effects of a growth hormone-releasing hormone analog on endogenous GH pulsatility and insulin sensitivity in healthy men. J Clin Endocrinol Metab. 2011. PMID 20943777. Stanley TL et al. Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation: a randomized clinical trial. JAMA. 2014. PMID 25038357. Grunfeld C et al. Recombinant human growth hormone to treat HIV-associated adipose redistribution syndrome: 12 week induction and 24-week maintenance therapy. J Acquir Immune Defic Syndr. 2007. PMID 17592343. Lo J et al. Low-dose physiological growth hormone in patients with HIV and abdominal fat accumulation: a randomized controlled trial. JAMA. 2008. PMID 18677023. Rudman D et al. Effects of human growth hormone in men over 60 years old. N Engl J Med. 1990. PMID 2355952. Liu H et al. Systematic review: the safety and efficacy of growth hormone in the healthy elderly. Ann Intern Med. 2007. PMID 17227934. Canadian product monograph for somatropin (Hoffmann-La Roche Limited), authorised December 2012. Health Canada Summary Basis of Decision for tesamorelin. US FDA approval of tesamorelin, November 2010.

More on this: Tesamorelin and Visceral Fat: The Trial Record.