Peptides That Have Primary Research
Some human research that backs up popular claims about peptides. Or doesn't.
Primary research will be your best friend when trying to understand if a claim about a peptide is legit, especially compared with advertisements and user testimonials. Of course, it is not the whole story, but it is a good starting point. The strength of primary research still depends on things like study design, sample size, replication, and whether the outcome actually matters clinically.
Semaglutide
Evidence Level: Strong
Wilding, J. P. H., et al. (2021). Once-weekly semaglutide in adults with overweight or obesity. New England Journal of Medicine, 384(11), 989-1002. https://doi.org/10.1056/NEJMoa2032183
This study looked at once-weekly semaglutide in adults with obesity or overweight plus at least one weight-related condition. It was a large randomized clinical trial and would be considered one of your primary research papers when it comes to semaglutide and weight loss (Wilding et al., 2021).
Open Primary Research
Tirzepatide
Evidence Level: Strong
Jastreboff, A. M., et al. (2022). Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine, 387(3), 205-216. https://doi.org/10.1056/NEJMoa2206038
SURMOUNT-1 was a phase 3 clinical trial that studied tirzepatide in adults with obesity or overweight plus at least one weight-related complication. It is one of the go-to primary research papers for tirzepatide and weight management (Jastreboff et al., 2022).
Open Primary Research
Retatrutide
Evidence Level: Shows Promise
Jastreboff, A. M., et al. (2023). Triple-hormone-receptor agonist retatrutide for obesity-A phase 2 trial. New England Journal of Medicine, 389(6), 514-526. https://doi.org/10.1056/NEJMoa2301972
Retatrutide has been studied in humans and showed substantial weight loss in this phase 2 trial. It is still being researched, so these results show promise but do not answer every question about long-term safety, effectiveness, or how broadly the results will apply (Jastreboff et al., 2023).
Open Primary Research
CJC-1295
Evidence Level: Human Pharmacology
Teichman, S. L., et al. (2006). Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. Journal of Clinical Endocrinology & Metabolism, 91(3), 799-805. https://doi.org/10.1210/jc.2005-1536
CJC-1295 has been shown to increase growth hormone and IGF-1 in humans. That does not prove that it can help with gaining muscle, losing fat, healing faster, recovering faster, or slowing aging (Teichman et al., 2006).
Open Primary Research
Ipamorelin
Evidence Level: Human Pharmacology
Gobburu, J. V. S., et al. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research, 16(9), 1412-1416. https://doi.org/10.1023/A:1018955126402
Ipamorelin has been studied in humans and has been shown to stimulate growth hormone release. There is not strong human evidence from this study that it can help you get jacked or turn back time (Gobburu et al., 1999).
Open Primary Research
Evidence Level: Not Much
Beck, E., et al. (2014). Randomized clinical evaluation of ipamorelin following bowel resection.
This study looked at ipamorelin in patients following bowel resection. It was generally tolerated, but the main efficacy outcome was not significantly different from placebo. I am putting this here because you should look at all of the research, not just the studies that back up what you want to hear.
Tesamorelin
Evidence Level: Strong
Falutz, J., et al. (2007). Metabolic effects of a growth hormone-releasing factor in patients with HIV. New England Journal of Medicine, 357(23), 2359-2370. https://doi.org/10.1056/NEJMoa072375
Tesamorelin was studied in people with HIV who had excess abdominal fat. The randomized trial showed a decrease in visceral adipose tissue compared with placebo (Falutz et al., 2007).
Open Primary Research
Evidence Level: Strong
Stanley, T. L., et al. (2014). Effect of tesamorelin on visceral fat and liver fat in HIV-infected patients with abdominal fat accumulation: A randomized clinical trial. JAMA, 312(4), 380-389. https://doi.org/10.1001/jama.2014.8334
Another human study found decreases in visceral fat and liver fat in people with HIV and abdominal fat accumulation (Stanley et al., 2014).
Bremelanotide
Evidence Level: Strong
Kingsberg, S. A., et al. (2019). Bremelanotide for the treatment of hypoactive sexual desire disorder: Two randomized phase 3 trials. Obstetrics & Gynecology, 134(5), 899-908. https://doi.org/10.1097/AOG.0000000000003500
These two phase 3 studies were done in premenopausal women with hypoactive sexual desire disorder. Bremelanotide improved measures of sexual desire and reduced distress related to low sexual desire compared with placebo (Kingsberg et al., 2019).
Open Primary Research
GHK-Cu
Evidence Level: Human Studies Done
Miller, T. R., Wagner, J. D., Baack, B. R., & Eisbach, K. J. (2006). Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. Archives of Facial Plastic Surgery, 8(4), 252-259. https://doi.org/10.1001/archfaci.8.4.252
This study was done in people who received CO2 laser skin resurfacing. Objective measures did not show significant differences between groups for erythema, wrinkles, or overall skin quality, although patient-reported satisfaction was higher in the GHK-Cu group. This is a good example of why it matters to look at exactly what a study found instead of only whether it sounds positive (Miller et al., 2006).
Open Primary Research
BPC-157
Evidence Level: Little Human Research
Lee, E., & Burgess, K. (2025). Safety of intravenous infusion of BPC157 in humans: A pilot study. Alternative Therapies in Health and Medicine, 31(5), 20-24.
I found a human pilot study indexed in PubMed, but it only included two participants and focused on short-term safety measures. I would not jump to conclusions about therapeutic benefits from a study this small (Lee & Burgess, 2025).
Open Primary Research
Here Is What Each Level Means
Evidence Level
Meaning
Strong
Backed up with solid human research for the specific claim or population discussed here.
Shows Promise
Some meaningful human research exists, but the peptide or use is still being studied.
Human Pharmacology / Human Studies
Human research has been done, but it may show a biological effect rather than a proven health benefit.
Not Much
Human research is limited or has not backed up many of the claims being made.
Little Human Research
There is too little human research to confidently back up broad claims.
These labels are an educational shorthand for this page, not a formal evidence-grading system.
Things to Remember
Just because something has been shown to affect a hormone or receptor does not mean it is going to have a meaningful effect on your health.
Animal studies are useful for research, but results in animals do not prove the same benefit will occur in humans.
FDA approval applies to a specific drug product and its approved conditions of use. It does not automatically apply to every product or compound that affects the same receptor.
Studies that show something does not work are just as important as studies that show that it does.
One very small study is not going to give you the same level of confidence as a large, well-designed randomized trial.
Some of these peptides are still being researched, so the evidence and regulatory status can change as new studies are completed.
More Places to Research
Disclaimer
This is meant to help you with your research. It is not a how-to guide on buying, using, mixing, dosing, reconstituting, or stacking peptides.
References
Beck, E., et al. (2014). Randomized clinical evaluation of ipamorelin following bowel resection.
Falutz, J., Allas, S., Blot, K., Potvin, D., Kotler, D., Somero, M., Berger, D., Brown, S., Richmond, G., Fessel, J., Turner, R., & Grinspoon, S. (2007). Metabolic effects of a growth hormone-releasing factor in patients with HIV. New England Journal of Medicine, 357(23), 2359-2370. https://doi.org/10.1056/NEJMoa072375
Gobburu, J. V. S., et al. (1999). Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers. Pharmaceutical Research, 16(9), 1412-1416. https://doi.org/10.1023/A:1018955126402
Jastreboff, A. M., et al. (2022). Tirzepatide once weekly for the treatment of obesity. New England Journal of Medicine, 387(3), 205-216. https://doi.org/10.1056/NEJMoa2206038
Jastreboff, A. M., et al. (2023). Triple-hormone-receptor agonist retatrutide for obesity-A phase 2 trial. New England Journal of Medicine, 389(6), 514-526. https://doi.org/10.1056/NEJMoa2301972
Kingsberg, S. A., et al. (2019). Bremelanotide for the treatment of hypoactive sexual desire disorder: Two randomized phase 3 trials. Obstetrics & Gynecology, 134(5), 899-908. https://doi.org/10.1097/AOG.0000000000003500
Lee, E., & Burgess, K. (2025). Safety of intravenous infusion of BPC157 in humans: A pilot study. Alternative Therapies in Health and Medicine, 31(5), 20-24.
Miller, T. R., Wagner, J. D., Baack, B. R., & Eisbach, K. J. (2006). Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. Archives of Facial Plastic Surgery, 8(4), 252-259. https://doi.org/10.1001/archfaci.8.4.252
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 randomized clinical trial. JAMA, 312(4), 380- 389. https://doi.org/10.1001/jama.2014.8334
Teichman, S. L., Neale, A., Lawrence, B., Gagnon, C., Castaigne, J.-P., & Frohman, L. A. (2006). Prolonged stimulation of growth hormone (GH) and insulin-like growth factor I secretion by CJC-1295, a long-acting analog of GH-releasing hormone, in healthy adults. Journal of Clinical Endocrinology & Metabolism, 91(3), 799-805. https://doi.org/10.1210/jc.2005-1536
Wilding, J. P. H., et al. (2021). Once-weekly semaglutide in adults with overweight or obesity. New England Journal of Medicine, 384(11), 989-1002. https://doi.org/10.1056/NEJMoa2032183
This article is meant to educate people about peptides and what we know about them. It is not recommending that anyone buy, stack, or use these drugs in any particular way. Please speak with your doctor about what may be best for you.