Tesamorelin
Tesamorelin is a synthetic peptide modeled after the hormone that signals the pituitary gland to release growth hormone. Researchers study its effects on growth hormone, IGF-1, abdominal fat distribution, metabolism, and other processes connected with body composition.
TESAMORELIN AT A GLANCE
WHAT IS TESAMORELIN?
Tesamorelin is a laboratory-made peptide containing 44 amino acids. Its structure is based on the complete sequence of natural growth hormone-releasing hormone, commonly called GHRH, with a small modification added to make the peptide more resistant to breakdown.
Natural GHRH is produced in the hypothalamus and signals the pituitary gland to release growth hormone. Tesamorelin was developed to reproduce this signal while remaining active in the body longer than the naturally occurring hormone.
HOW DOES TESAMORELIN WORK?
Tesamorelin attaches to GHRH receptors on cells in the anterior pituitary gland. This encourages the pituitary to release growth hormone in pulses. Growth hormone then acts on the liver and other tissues, increasing the production of insulin-like growth factor 1, better known as IGF-1.
Growth hormone and IGF-1 influence fat metabolism, tissue growth, glucose regulation, and body composition. Research suggests that Tesamorelin can reduce visceral adipose tissue—the fat stored deep within the abdomen around internal organs—without producing the same degree of change in subcutaneous fat beneath the skin.
Areas of Research
Tesamorelin research explores how stimulating the body’s own growth hormone pathway affects fat distribution, metabolism, and tissues that depend on this hormonal system.
VISCERAL ABDOMINAL FAT
Examining changes in the deeper abdominal fat associated with HIV-related changes in body-fat distribution.
GROWTH HORMONE AND IGF-1
Studying how GHRH-receptor stimulation affects natural growth hormone pulses and circulating IGF-1 levels.
LIVER FAT AND METABOLISM
Investigating possible changes in fat stored within the liver, triglycerides, glucose regulation, and other metabolic measurements.
MUSCLE AND PHYSICAL FUNCTION
Exploring whether increased growth hormone signaling affects muscle size, strength, energy use, or physical ability in people with HIV and other studied populations.
Research Highlights
Large clinical trials involving adults with HIV-associated abdominal fat accumulation found that Tesamorelin reduced visceral adipose tissue while generally preserving subcutaneous and limb fat. One 12-month study reported an approximately 18% reduction among participants who continued treatment. The abdominal-fat improvements were lost relatively quickly when participants stopped receiving Tesamorelin, showing that its effects were not permanent.
Smaller studies have explored additional areas. Research involving people with HIV and fatty liver disease reported reductions in liver fat, while a 2025 study found a reduction in waist circumference but no clear improvement in cognitive performance compared with standard care. Researchers continue studying liver health, muscle function, and metabolic changes, but these uses remain investigational. Increased IGF-1, fluid retention, joint discomfort, injection-site reactions, and changes in glucose regulation are among the concerns monitored during treatment.
WHAT IS TESAMORELIN MOST COMMONLY RESEARCHED FOR?
Tesamorelin is most commonly researched for excess visceral abdominal fat associated with HIV-related lipodystrophy. This is a change in body-fat distribution that can occur in some people living with HIV, particularly in connection with long-term infection and treatment. Although Tesamorelin reduces this specific type of abdominal fat, it is not approved as a general weight-loss medication and may not cause a meaningful change in overall body weight.
HOW DOES TESAMORELIN FIT INTO PEPTIDE RESEARCH?
Tesamorelin helps researchers explore what happens when a peptide activates a natural hormone pathway instead of supplying the final hormone directly. It begins a sequence involving the pituitary gland, growth hormone, IGF-1, and metabolic activity in different tissues. Its research also shows that body-fat location can change even when total body weight changes very little.
WHAT MAKES TESAMORELIN UNIQUE?
Tesamorelin stands out because it is one of the relatively few peptides with an FDA-approved medical use. It includes all 44 amino acids of natural GHRH but has an added chemical group that helps protect it from rapid breakdown. Its ability to reduce visceral fat while largely preserving subcutaneous fat also distinguishes it from treatments intended to produce broader weight loss.
HOW IS TESAMORELIN DIFFERENT FROM SERMORELIN?
Tesamorelin and Sermorelin both activate the GHRH receptor and encourage the pituitary gland to release growth hormone, but their structures and approved histories differ. Tesamorelin is a modified version of the complete 44-amino-acid GHRH sequence and is FDA approved for reducing excess abdominal fat in adults with HIV-associated lipodystrophy. Sermorelin contains only the first 29 amino acids of GHRH and was previously approved for certain pediatric and diagnostic uses, but no FDA-approved Sermorelin medication is currently available.
WHAT HAVE RESEARCHERS LEARNED ABOUT TESAMORELIN SO FAR?
Researchers have learned that Tesamorelin can increase growth hormone and IGF-1 activity and reduce visceral abdominal fat in many adults with HIV-associated lipodystrophy. Studies also show that individual responses vary and that abdominal fat may return after treatment ends. Findings involving liver fat and certain metabolic measurements have encouraged additional research, but benefits outside its approved use have not been firmly established. Increased growth hormone signaling can also create risks, particularly for people with glucose-regulation problems, active cancer, or disrupted pituitary function.
IS RESEARCH ON TESAMORELIN CONTINUING TODAY?
Yes. Researchers continue studying Tesamorelin in connection with liver fat, metabolic health, muscle function, physical performance, nerve injury, and complications associated with HIV. A current clinical trial is examining whether adding Tesamorelin to exercise can improve muscle health and physical function in adults with HIV. Larger studies are still needed to determine whether findings outside its approved use translate into meaningful and lasting benefits.