Tesamorelin explained: the peptide with real human trials behind it

• What it is: a stabilized copy of GHRH, the hormone that tells the pituitary to release growth hormone [3][7].
• The headline result: in a 412-person trial, deep belly fat dropped 15.2% in 26 weeks, while it rose 5.0% on placebo [1].
• Bonus findings: lower triglycerides [1], 37% less liver fat in a year-long trial [5], and better scores on thinking tests in older adults [6].
• The catch: those were prescription-drug trials in specific patient groups. Research-grade tesamorelin isn't approved for any use in people.

The body runs growth hormone on a two-step relay: the hypothalamus, deep in the brain, sends a signal called GHRH (growth hormone–releasing hormone), and the pituitary answers by releasing growth hormone.

Tesamorelin is a lab-made GHRH with the same 44 amino acids as the human hormone, plus one upgrade: a small six-carbon chain attached to the front end, which makes it more stable in blood than natural GHRH [7].

Now the plot twist: most research peptides never get anywhere near a pharmacy, but tesamorelin did. Under the brand name Egrifta, it became the first treatment approved to reduce excess belly fat in people with HIV-associated lipodystrophy [3].

At a molecular weight of about 5,136, it's a big peptide — more than three times the size of BPC-157.

Tesamorelin contains no growth hormone at all; it's a messenger that prompts the pituitary to make and release its own [3].

The easiest way to see it working is IGF-1, a hormone that rises when growth hormone does. In the big 2007 trial, IGF-1 went up 81% on tesamorelin and fell 5% on placebo [1].

• Deep belly fat. Visceral fat is the deep kind packed around the organs, and in the 2007 trial of 412 people with HIV-related fat gain, it fell 15.2% on tesamorelin and rose 5.0% on placebo. Triglycerides dropped by 50 mg/dL, versus a 9 mg/dL rise [1].
• It went after the right fat. Across two Phase 3 trials with 806 people, visceral fat fell by a 15.4% treatment effect, while the fat just under the skin barely moved [2].
• The results held. People who stayed on it for a full year kept the loss: visceral fat was down 17.5% at week 52 [2].
• Liver fat. A 2014 trial saw less visceral fat and less liver fat after six months [4]. In a 2019 year-long trial, liver fat fell by 37%, and 35% of the tesamorelin group got below the 5% fatty-liver line, versus 4% on placebo [5].
• The brain. In 152 adults aged 55 to 87, 20 weeks of tesamorelin improved executive function — the mental skills behind planning and switching between tasks. It also raised IGF-1 by 117% and cut body fat by 7.4% [6].

• These were drug trials. The results come from a prescription medicine that was given to specific groups — mostly people with HIV-related fat gain — under medical supervision.
• Stop, and the fat comes back. When people switched to placebo, the visceral fat returned [3].
• It isn't side-effect free. Trials logged injection-site reactions, joint pain, headache and swelling [3], and in 2007 more people left the tesamorelin group because of side effects [1]. In one trial, fasting blood sugar rose in the first two weeks before settling [4].
• The research reagent is not the drug. The tesamorelin we sell is not Egrifta, and it isn't approved for use in people for anything.

Long peptides are harder to make cleanly, because every extra amino acid is another chance for the synthesis to slip — and tesamorelin has 44 of them plus a chemical cap. The only way to know what came out is to test it. So before any batch goes on sale, an outside lab checks:

• Purity by HPLC. The exact figure the lab measured, to two decimals. Never a “99%+” floor.
• Identity by mass spectrometry. The measured mass has to match tesamorelin, cap and all.

Every tesamorelin batch we've released is on the tesamorelin lab-reports page, with its signed certificate. If a vial doesn't match its report, test it at any lab you like and we'll refund it in full.

Tesamorelin is the rare research peptide with serious human data behind it: large, placebo-controlled trials showing less deep belly fat, less liver fat and better lipids — in the groups studied, on a prescription drug. If you're reading up on the growth hormone system, our ipamorelin guide covers a peptide that reaches the same system through a different receptor.