CJC-1295 and ipamorelin work through the growth hormone axis, not the testosterone-producing pathway. There are human studies demonstrating these peptides raise growth hormone and IGF-1 in adult participants, who in the main studies happened to be male. However, no dedicated study isolates results specific to male physiology, testosterone interaction, or athletic performance for either compound.
Benefits of CJC-1295 and Ipamorelin for Men
It is worth clarifying immediately something that is often lost in the way this topic is researched. The main human pharmacological studies on CJC-1295 did indeed recruit adult male and female volunteers together. The fundamental ipamorelin studies were also conducted specifically on men, in several instances. However, neither of these studies was designed to isolate or report findings as specific to male physiology. The available hormonal data pertain to the research population generally, not dedicated „for men” discoveries [1], [2]. In the main CJC-1295 study, healthy adults aged 21–61 years were given single escalating doses and multiple dosing regimens. Researchers observed a dose-dependent increase in growth hormone that lasted for six days or longer, and elevations in IGF-1 that persisted for nine to eleven days after a single injection [1]. The original human pharmacokinetic study of ipamorelin specifically used male volunteers. It demonstrated a short, sharp pulse of growth hormone peaking around 40 minutes post-administration, with a two-hour half-life [2]. A separate study measuring the pulsatile release of growth hormone after CJC-1295 was also conducted specifically on men, aged 20–40 years [3].
While there is therefore true hormonal data in humans that includes males, framing this as „CJC-1295 and Ipamorelin benefits for men” specifically overstates what these studies were designed to show. None of them compared outcomes between males and females or reported sex-specific outcomes. As discussed in earlier articles in this series, there are essentially no equivalent studies involving females at all. This means that the available data reflects general adult human physiology, not a male-specific benefit profile.
CJC-1295 and Ipamorelin and Testosterone in Men
Growth hormone and testosterone operate through separate hormonal control systems in the body. There is a growth hormone axis, which CJC-1295 and ipamorelin act upon. And there is the hypothalamic-pituitary-gonadal axis, which governs testosterone production. No human trials identified within this research series have measured testosterone levels in men after administration of CJC-1295 or ipamorelin. A review analyzing growth hormone stimulators as a potential adjunctive approach in men with hypogonadism — men with clinically low testosterone — examined how these compounds might support body composition and certain symptoms associated with low testosterone, as an adjunct alongside standard testosterone replacement therapy. The proposed benefit, however, was described as an indirect metabolic effect, not a direct increase in testosterone itself. The review authors were clear that clinical data supporting this specific application remain limited [4].
Regarding the idea of combining these peptides with testosterone replacement therapy (TRT), no dedicated clinical trials have tested this combination. Questions about the effects of interactions, safety, or additional benefit when used alongside TRT cannot, therefore, be answered with direct evidence. The review discussed above raises this as a conceptual possibility worthy of further investigation—an unvalidated protocol [4].
The basic studies of ipamorelin are also worth noting here. It has been specifically shown not to significantly raise cortisol or ACTH, the stress hormone pathway. This sets it apart from some older growth hormone-releasing peptides. The same study did not measure or report on testosterone [5].
Taking all of this into account, describing CJC-1295 or ipamorelin as T-boosting in men, or as a validated protocol for TRT supplementation, goes beyond what current evidence supports.
CJC-1295 and Ipamorelin for men's athletic performance
Claims regarding athletic performance, strength, muscle growth, or bodybuilding benefits specifically in men are based almost entirely on the general physiology of growth hormone and IGF-1, rather than direct performance outcome studies. This aligns with what was discussed in earlier articles in this series regarding muscle growth and fat burning. The most directly relevant supporting data remains a single animal study. A 2026 review in the American Journal of Sports Medicine noted that CJC-1295 combined with ipamorelin significantly improved maximal muscle tension in a mouse model of steroid-induced muscle loss. However, this finding is clearly limited to animal research. It has not been replicated in human studies, let alone one that specifically measured outcomes in male athletes [6].
Broader reviews of the use of injectable peptides in sports medicine have grouped CJC-1295 and ipamorelin among growth hormone axis compounds that remain investigational. These reviews clearly note that clinical evidence supporting their use for athletic performance or muscle growth in humans, men or women, is insufficient. They also note that unregulated use in athletic and bodybuilding populations carries additional risks associated with inconsistent product quality [6], [7].
Regarding fat burning specifically, the only clinical study designed to test the related outcome of visceral fat reduction was not completed, as discussed in earlier articles in this series. No men's body composition outcome-specific data exists separately from this unfinished study [1].
Taking this into account, any claims describing CJC-1295 and ipamorelin as providing proven strength, muscle, or performance benefits specifically for men should be understood as theoretical extrapolations from hormonal physiology and limited animal data—not demonstrated human trial results.
Limitations of current evidence
Human studies on CJC-1295 and ipamorelin do include male participants. In some cases, such as pharmacokinetic and pulsatility studies of ipamorelin, they were conducted exclusively on men. However, none of these studies were designed to isolate male-specific outcomes, compare results by sex, or measure testosterone, athletic performance, or bodybuilding-relevant endpoints.
Claims about TRT connection protocols, testosterone increases, or male-specific performance benefits go far beyond what available research has actually measured.
Disclaimer
This content is for educational and informational purposes only and should not be interpreted as medical advice, diagnosis, or therapeutic recommendation. CJC-1295 and ipamorelin remain research compounds and are not approved by the FDA or European Medicines Agency for any medical use, whether used individually or in combination. No published human studies have measured testosterone levels, athletic performance outcomes, or male-specific effects for either compound. Anyone considering testosterone replacement therapy or performance-related treatment should consult with a qualified healthcare professional for evidence-based options.
References
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
Gobburu, J. V., Agersø, H., Jusko, W. J., & Ynddal, L. (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
[3] Ionescu, M., & Frohman, L. A. (2006). Pulsatile secretion of growth hormone (GH) persists during continuous stimulation by CJC-1295, a long-acting GH-releasing hormone analog. Journal of Clinical Endocrinology & Metabolism, 91(12), 4792–4797. https://doi.org/10.1210/jc.2006-1702
[4] Sinha, D. K., Balasubramanian, A., Tatem, A. J., Rivera-Mirabal, J., Yu, J., Kovac, J., Pastuszak, A. W., & Lipshultz, L. I. (2020). Beyond the androgen receptor: The role of growth hormone secretagogues in the modern management of body composition in hypogonadal males. Translational Andrology and Urology, 9(Suppl. 2), S149–S159. https://doi.org/10.21037/tau.2019.11.30
[5] Raun, K., Hansen, B. S., Johansen, N. L., Thøgersen, H., Madsen, K., Ankersen, M., & Andersen, P. H. (1998). Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology, 139(5), 552–561. https://doi.org/10.1530/eje.0.1390552
[6] Mayfield, C. K., Bolia, I. K., Feingold, C. L., Lin, E. H., Liu, J. N., Hatch, G. F. R., Gamradt, S. C., & Weber, A. E. (2026). Injectable peptide therapy: A primer for orthopaedic and sports medicine physicians. American Journal of Sports Medicine, 54(1), 223–229. https://doi.org/10.1177/03635465251357593
[7] Coutinho, L. F. D., De Oliveira Neves, L. F., & Camilo, R. P. (2026). A new era of doping? Use of peptide and peptide-analog drugs in recreational and professional sport and bodybuilding: A critical review. Journal of Sports Medicine and Physical Fitness, 66(7), 880–885. https://doi.org/10.23736/S0022-4707.26.17773-1