# Muscle gain: what the research says The research on muscle gain for the two quiz items is indirect. CJC-1295 and ipamorelin have small human studies in healthy adults that measured growth hormone levels, not muscle. BPC-157 has rat studies of injured muscle and tendon and a few human reports with no control group. No human study found for these guides measured muscle mass after any of the three peptides. Growth hormone leaves your pituitary gland in bursts, not as one steady flow. A hypothalamus signal called GHRH sets when each burst comes, and ghrelin, a stomach hormone, also prompts the pituitary. CJC-1295 copies part of GHRH, and ipamorelin copies part of ghrelin’s signal. So the human research on both starts and ends with hormone levels. The [CJC-1295 study guide](/learn/cjc-1295/what-does-cjc-1295-do) and the [ipamorelin study guide](/learn/ipamorelin/what-is-ipamorelin) set out what those studies measured. The quiz’s Muscle gain goal has two options, “Build muscle” and “Train harder and protect my tendons”. The research behind the second option is on BPC-157, and most of it comes from rats with injured muscle or tendon. The [BPC-157 study guide](/learn/bpc-157/bpc-157-study-findings) sorts that evidence by type. This page keeps every finding next to its study type, so that a hormone result or a rat result is never read as a muscle result in people. ## What research exists on CJC-1295, ipamorelin, BPC-157 and muscle? The research on CJC-1295, ipamorelin, BPC-157 and muscle is indirect, and none of it is a human muscle trial. CJC-1295 and ipamorelin have small human studies that measured growth hormone and IGF-I, a growth-related hormone, in healthy adults. BPC-157 has rat studies of injured muscle and tendon, and three small human reports without a control group. No human study found for these guides measured muscle mass after any of them. Each kind of study answers a different question. A hormone study asks whether a blood level changed. A rat injury study asks whether a damaged tissue healed differently. A muscle trial in people would ask whether muscle size or strength changed, and that is the study nobody has published for these three peptides. The table below lists the two quiz items with the quiz’s own line on what studies found and the type of study behind it. Each study guide then sets out the individual papers, with the model, the result and the main limit of each. ## What has the research not shown about these peptides and muscle gain? The research has not shown that CJC-1295, ipamorelin or BPC-157 increases muscle mass or strength in people. No published human trial found measured muscle mass or strength after CJC-1295 or after ipamorelin. A 2026 narrative review, an expert summary rather than a trial, found no peer-reviewed support for body-composition or performance effects of CJC-1295 (Dominikowski et al., Frontiers in Endocrinology, 2026). For BPC-157, the human reports did not measure muscle mass. The same review describes controlled evidence for the CJC-1295 and ipamorelin pair, whether for synergy or for body-composition change in healthy people, as limited. No controlled human trial of the pair was found. Most human CJC-1295 results also concern the form with DAC, a chemical add-on, and no published human study of the form without DAC was found. The [CJC-1295 (No DAC) and ipamorelin reference material](/shop/cjc-1295-ipamorelin) is the form without DAC, so those human results are background for it, not direct evidence. BPC-157 has its own limits. A 2026 review in *Pharmaceutics* estimated that more than 80% of BPC-157 papers come from one research group at the University of Zagreb, and called the lack of independent replication a significant limitation (Mateescu et al., 2026). A rat result is a hypothesis about people, not a measurement of what happens in one. ## Do CJC-1295 and ipamorelin studies show muscle growth? CJC-1295 and ipamorelin studies show hormone changes, not muscle growth. In two placebo-controlled trials of healthy adults aged 21 to 61, CJC-1295 with DAC raised growth hormone and IGF-I (Teichman et al., Journal of Clinical Endocrinology & Metabolism, 2006). Ipamorelin raised growth hormone in a 1999 study of healthy men that measured hormone levels only (Gobburu et al., Pharmaceutical Research, 1999). Neither study measured muscle size or strength. The nearest muscle data come from animals, and each belongs to its own model. In mice bred without the GHRH gene, lean mass relative to body size was normal in every CJC-1295 group. That is a growth-deficient mouse model, not healthy muscle and not people (Alba et al., 2006). In female rats in a steroid-induced model of muscle and bone loss, rats that also received ipamorelin had higher maximum calf-muscle tension than rats given the steroid alone, a rat result that does not establish a human one (Andersen et al., *Growth Hormone & IGF Research*, 2001). Your body makes growth hormone in pulses, and a study can measure every pulse without saying anything about your muscles. The [CJC-1295 hub](/learn/cjc-1295) holds the other CJC-1295 guides, including its side effects. ## What do BPC-157 studies show about muscle and tendons? BPC-157 studies reported repair of injured muscle and tendon in rats, not growth of healthy muscle. After a complete cut of the quadriceps, treated rats had a higher load before failure and larger myofibril diameters over 72 days (Staresinic et al., Journal of Orthopaedic Research, 2006). After the Achilles tendon was cut, treated rats had a higher load before failure and better walking scores (Staresinic et al., 2003). Rat results do not establish what happens in people. A crush-injury rat study found less haematoma and swelling, and better function, over 14 days (Novinscak et al., *Surgery Today*, 2008). Repair of damage is a different outcome from growth of healthy muscle, and none of these rat abstracts gives a group size. The human record is thin. A 2025 systematic review included 35 preclinical studies and one clinical study, its selected evidence set rather than every BPC-157 paper (Vasireddi et al., *HSS Journal*, 2025). The three published human pilot reports had 17, 12 and 2 participants, had no control group, and none measured muscle mass. The [BPC-157 hub](/learn/bpc-157) holds the side-effect record and the other BPC-157 guides. ## Comparison Each row is one quiz item for the Muscle gain goal: the quiz’s own line on what studies found, the type of study behind that line, and links to the item’s study guide and product page. A hormone level or an animal result is not a muscle result in people. Not a comparison of medicines. | Quiz item | What studies found | Study type | Read the research | Product | | --- | --- | --- | --- | --- | | CJC-1295 + Ipamorelin | Raised growth-hormone levels in small human studies. None of those studies measured muscle gain. | Small human studies | [CJC-1295 + Ipamorelin study guide](/learn/cjc-1295/what-does-cjc-1295-do) | [CJC-1295 + Ipamorelin](/shop/cjc-1295-ipamorelin) | | BPC-157 | Linked to faster tendon healing in animal studies. Human evidence is limited. | Animal studies | [BPC-157 study guide](/learn/bpc-157/bpc-157-study-findings) | [BPC-157](/shop/bpc-157) | ## Frequently asked questions ### Have studies found that CJC-1295 and ipamorelin build muscle? No published human trial found has measured muscle mass or strength after CJC-1295, ipamorelin or the two together. A 2026 narrative review describes controlled evidence for meaningful body-composition change from the pair in healthy people as limited; that is the review’s assessment, not a trial result (Dominikowski et al., *Frontiers in Endocrinology*, 2026). ### Is there a human study of BPC-157 and muscle? The FDA briefing and PubMed records searched on 14 October 2026 did not find a human study that measured muscle mass after BPC-157. The muscle results come from rats with cut or crushed muscle, which tested the repair of an injury, not the growth of healthy muscle (Staresinic et al., 2006; Novinscak et al., 2008). ### Does a rise in growth hormone mean more muscle? A rise in growth hormone is a blood-test result, not a muscle result. A review that pooled trials of growth hormone itself found changes in body fat and lean mass, but no rise in muscle strength or aerobic capacity (Hermansen et al., *Growth Hormone & IGF Research*, 2017). That review tested growth hormone, not CJC-1295 or ipamorelin, so it cannot supply a result for either. ### Are ipamorelin and BPC-157 approved medicines? The FDA’s 2024 review found that ipamorelin is not a component of any FDA-approved drug (FDA review, 19 August 2024). No approved product containing BPC-157 appeared in the FDA’s search of approved products in any country, which is a search result and not a statement from every regulator (FDA briefing document, July 2026). ## Citations - Teichman SL, Neale A, Lawrence B, Gagnon C, Castaigne JP, Frohman LA.. Journal of Clinical Endocrinology & Metabolism. 2006;91(3):799-805. DOI: 10.1210/jc.2005-1536 - Gobburu JV, Agersø H, Jusko WJ, Ynddal L.. Pharmaceutical Research. 1999;16(9):1412-1416. DOI: 10.1023/a:1018955126402 - Alba M, Fintini D, Sagazio A, et al.. American Journal of Physiology-Endocrinology and Metabolism. 2006;291(6):E1290-E1294. DOI: 10.1152/ajpendo.00201.2006 - Andersen NB et al.. Growth Hormone & IGF Research. 2001;11(5):266-272. DOI: 10.1054/ghir.2001.0239 - Dominikowski A, Rękoś Z, Olejarz M, et al.. Frontiers in Endocrinology. 2026;17:1822475. DOI: 10.3389/fendo.2026.1822475 - Hermansen K et al.. Growth Hormone & IGF Research. 2017;34:38-44. DOI: 10.1016/j.ghir.2017.05.005 - Staresinic M et al.. Journal of Orthopaedic Research. 2003;21(6):976-983. DOI: 10.1016/S0736-0266(03)00110-4 - Staresinic M et al.. Journal of Orthopaedic Research. 2006;24(5):1109-1117. DOI: 10.1002/jor.20089 - Novinscak T et al.. Surgery Today. 2008;38(8):716-725. DOI: 10.1007/s00595-007-3706-2 - Vasireddi N et al.. HSS Journal. 2025;21(4):485-495. DOI: 10.1177/15563316251355551 - Mateescu DM et al.. Pharmaceutics. 2026;18(5):625. DOI: 10.3390/pharmaceutics18050625 [Take the quiz: Muscle gain](https://stack.formlaboratories.com) Research use only — not for human or animal use. ## Articles in this hub --- Canonical page: https://www.formlaboratories.com/learn/muscle-gain Form Laboratories - Perth-based research-use-only peptide supplier, shipping Australia-wide. - Site guide for agents: https://www.formlaboratories.com/llms.txt - Sitemap: https://www.formlaboratories.com/sitemap.xml - Full catalogue: https://www.formlaboratories.com/shop - Contact: hello@formlaboratories.com All materials are supplied for laboratory research use only - not for human or veterinary use, and nothing on this site is medical advice.