Published April 23, 2026 04:45PM
My knee-jerk take on peptides is, admittedly, self-contradictory. I think athletes who take them are cheating; I also think they don’t work. That doesn’t make a lot of sense, so I’ve been intending for a while to dig into the scientific literature to get a more informed take.
A new review in the journal Sports Medicine provides just the spur I’ve been waiting for. Christopher Mendias and Tariq Awan, sports medicine physicians at a clinic in Phoenix, gather the evidence on ten peptides that are currently making the rounds on social media as potential athletic performance-boosters. Their review joins a couple of other recent ones in places like the American Journal of Sports Medicine and Sports Medicine Update. Together, they offer a guide to what’s being promised, what the evidence so far says, and what scientists and physicians think about it.
Some definitions to start. Peptides are relatively short chains of amino acids: shorter than proteins, but longer than individual amino acids. Our bodies produce thousands of different peptides with various functions: insulin and oxytocin are well-known examples. Common therapies such as GLP-1 drugs like Ozempic are also peptides.
The reason athletes have become interested in peptides is that they serve as signaling molecules. Instead of taking, say, human growth hormone, you can take a peptide that tells your body to produce more human growth hormone. Whether this actually enhances performance isn’t entirely clear; neither is it clear whether this approach produces the same potential side effects—diabetes, cancer, acromegaly—as taking human growth hormone directly. But the prospect of using peptides to turn on or off bodily functions like cell repair and blood vessel growth is understandably alluring to athletes.
Which Peptides Are Athletes Using?
Mendias and Awan focus on ten types of peptides, most of which are currently only available on the gray market, though the FDA is reportedly planning to lift restrictions soon. Even if those restrictions are lifted, all but two (GHK-Cu and SS-31) are banned by the World Anti-Doping Agency for competitive athletes. Here’s their list:
1. AOD-9604
Originally developed as an anti-obesity drug, it seemed to be very effective in rodents but failed in human studies with over 900 patients. Remember that point—effective in rodents, useless in humans—because it’s going to be a theme.
Given that GLP-1 drugs are more effective for weight loss, the main reason people are still interested in AOD-9604 is because of a 2015 study suggesting that it might help cartilage regeneration in osteoarthritic rabbits. No one has shown a comparable benefit in humans.
2. BPC-157
This is a big one, part of the so-called Wolverine stack (along with TB-500) hyped by Joe Rogan and allegedly used by some NCAA cross-country athletes. It’s supposed to promote the formation of new blood vessels and, in doing so, promote healing in chronic muscle, tendon, and bone injuries.
There’s a bunch of encouraging preclinical data—that is, animals and test tubes—but essentially no human studies other than a seriously unconvincing retrospective survey with no control group in Alternative Therapies in Health and Medicine. The internet loves it, though.
3. CJC-1295
Back in 2006, a study found that CJC-1295 triggered sustained rises in human growth hormone and insulin-like growth factor-I. These days, it’s promoted to build muscle, lose fat, and speed up healing.
On the other hand, one study found that 94 percent of patients experienced adverse reactions, and another trial was halted after a patient died (though it wasn’t clear whether the drug caused the death). It’s probably fair to say CJC-1295 has real effects, rather than just being a placebo—the question is whether you really want all the effects. There’s a reason few people take growth hormones recreationally.
4. FS-344 (follistatin)
This peptide inhibits the cellular signals that cause muscles to atrophy. In animal studies, along with one human study in people with muscular dystrophy, it works to build muscle—if you get gene therapy to increase the body’s continuous production of follistatin.
If you just want to inject the follistatin peptide directly (which is how these peptides are generally administered), then you would have to do it several times a day to keep levels elevated. Medias and Awan’s assessment is that this means it has “little practical utility.”
5. GHK-Cu (copper peptide)
Copper peptides are mostly promoted in topical creams for skincare, aiming to enhance collagen production. But it’s also promoted for joint pain and overall health, in both oral and injectable forms. Oral GHK-Cu is probably a bad idea, because it will break down in your stomach and release the copper, which can have various negative health effects. As for injections, there’s no evidence either way.
6. Ipamorelin
Ipamorelin activates the receptor for ghrelin, a hormone that triggers hunger. The idea here is that if you’re trying to get big but can’t manage to get enough calories and protein in, ipamorelin will help you eat more. The idea has been tested in patients following abdominal surgery, and it appeared to be safe but ineffective. Medias and Awan also flag some potential concerns, including messing up your insulin sensitivity or possibly speeding up tumor growth.
7. MOTS-c (mitochondrial-derived peptide)
This is an “artificial exercise” candidate, thought to trigger some of the same cellular responses as exercise, like boosting endurance and improving metabolic health. It successfully prevented obesity and insulin resistance in mice, but there’s no human data, either for safety or effectiveness.
8. Sermorelin and tesamorelin
These are peptides that, like CJC-1295, temporarily increase levels of human growth hormone and insulin-like growth factor-I. There’s quite a bit of human research attempting to change body composition, particularly losing fat. There’s also encouraging animal data suggesting it might speed up injury recovery.
All in all, Medias and Awan sound more positive about this one than most of the others. Still, they point out, there are serious questions about the pros and cons of any therapy that produces sustained elevations of growth hormones, with evidence that it could shorten lifespan.
9. SS-31 (elamipretide)
Elamipretide is supposed to boost mitochondrial function. Unlike most of the peptides listed here, it has actually gone through the full process of getting FDA approval, in this case to treat Barth syndrome, a condition caused by malfunctioning mitochondria.
The question is: What else can it do? There’s animal data suggesting it might help with concussions, and it boosted treadmill endurance in a mouse study. One human study found that it boosted mitochondrial function in older adults with bad mitochondria, but that didn’t translate to any changes in fatigue resistance.
10. TB4 and TB-500
TB4 is released by immune cells after injury and helps initiate the repair process; TB-500 is a subcomponent of TB4. There’s evidence in animals (though not humans) that it can help with wound healing and tissue regeneration. The hype—TB-500 is part of the Wolverine stack—focuses on injury recovery.
The caveat? High TB4 levels are correlated with the progression of tumors through some of the same mechanisms that enhance wound healing. That’s just a theoretical risk at this point—but that’s the kind of risk that we have clinical trials for.
So what’s the overall take on peptides? It’s hard to make blanket statements. Each of these peptides has different mechanisms of action, different levels of evidence, different potential risks. None of them comes anywhere close to having reasonable evidence that they actually work in humans, but if you’re a “that empty glass has a few drops of water in it” kind of guy, most of them also haven’t been shown not to work.
For me, the biggest benefit of going through these journal papers is that it soothes my FOMO. Given that they’re almost all banned by WADA, I was never going to take any of them anyway. But with all the social media hype, it’s sometimes hard not to wonder whether you’re missing out on some amazing injury cure or performance boost. Based on the evidence so far, I wouldn’t take them even if they were legal.
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