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The Human Lab Rats Injecting Themselves with Peptides

These experimental peptides are essentially illegal and may not even work, but fitness influencers can’t get enough of them.

When the Liver King fell from grace, the leaked list of the drugs he was on raised many eyebrows. The Liver King, Brian Johnson, is a buff social media influencer who pressed his followers to adopt an “ancestral lifestyle” and stay away from chemicals, Wi-Fi signals, and modern bedding. He claimed he achieved his incredible physique the natural way; it turns out he was full of performance-enhancing drugs, which he confessed to after private emails surfaced. (He is doing well, by the way, with 2.1 million followers on Instagram and a still-active dietary supplement shop. He has traded in his baseball cap for a cowboy hat and a temporary eye patch following a workout injury.)

This list of performance-enhancing drugs caught the attention of Ryan Humiston, a fitness YouTuber with nearly 2 million subscribers on the platform. This is how Humiston found out about peptides. He has since made a number of videos about them, calling them “a GAME CHANGER” and saying his muscles are “fuller and rounder.”

He is not the only one promoting these so-called peptides. Workout gurus are praising their virtues, and science podcasting juggernaut Andrew Huberman takes one called sermorelin three to five nights a week to help him sleep. “It’s great,” he has said, “you recover fast.”

Peptides are all the rage, but everything about them is confusing. Many have to be injected, though some can be taken by mouth. Many stimulate your body to produce growth hormone, but some don’t. Most are peptides, but some are not.

These experimental drugs came about to solve real problems. Now, they exist as lucrative black-market solutions to men who want the alleged benefits of Gwyneth Paltrow’s goop without the pastel colours.

Gym rats

Peptides are short chains of amino acids. Past a certain length, we refer to them as proteins. Our bodies are full of peptides helping us stay alive, like insulin and oxytocin. The specific peptides that have taken the fitness world by storm, however, tend to be involved in the production of growth hormone.

Growth hormone, as its name suggests, stimulates growth. Children who, often for unclear reasons, do not make enough of it do not grow as tall as their peers. The primary treatment consists in regular injections of growth hormone, but because of needle pain and the considerable expense, researchers began to look for other ways to boost the levels of growth hormone in these children. Also, growth hormone levels drop as we get older, and there was interest in seeing if tweaking these levels might benefit older adults struggling with loss of bone and muscle mass and increases in body fat.

The pituitary gland, dangling from the bottom of our brain, secretes growth hormone in pulses, and this secretion is regulated by two main hormones: somatostatin blocks its release, while growth hormone-releasing hormone (or GHRH), as its name implies, encourages it. In the 1970s, however, research led by Dr. Cyril Bowers showed another way to influence the release of growth hormone. He discovered that by modifying a painkilling peptide our bodies produce, he had created molecules that could also increase production of growth hormone. To do this naturally, our body produces GHRH; Bowers’ synthetic peptides, which had a similar effect, were called GHRPs, or growth hormone-releasing peptides. You will also see them referred to as a type of growth hormone secretagogues, meaning that they cause growth hormone to be secreted.

Over the years, many GHRPs were designed. They were given numbers, like GHRP-2 and GHRP-6, or scientific names like hexarelin or ipamorelin. The peptides that have captured the attention of fitness influencers in 2023 include GHRPs, but also other experimental drugs like BPC 157, a shortened form of a peptide discovered in stomach juices; GHK, a tiny peptide often bound to copper; and MK-677, a Merck drug that is not a peptide but that behaves just like the peptide GHRP-6.

The story of these diverse experimental drugs is eerily similar. A laboratory synthesizes it for the first time, discovers it seems to have interesting properties, and spends many years studying it in rodents. What is measured in these rats and mice (and occasionally in small groups of human volunteers) is often not a hard endpoint like muscle strength or weight loss, but surrogate biomarkers: molecules in the blood that have an indirect link to a hard endpoint. It’s like wondering if you have a flat tire, but instead of leaving your car to check, you rely on the wobbly handling of your car on the road to indicate that you probably have a flat tire. It’s an easier, indirect measurement, but the wobbliness could be due to something else. BPC 157 was studied almost exclusively by the same Croatian team that created it, doing rat study after rat study, while MK-677 was the domain of the Merck Research Laboratories in New Jersey, whose scientists conducted multiple small trials in humans in the 1990s, trying to see if the drug had interesting effects on a variety of surrogate markers.

These drugs were promising early on, but many were abandoned for either failing to show clear benefits or for allegedly causing severe side effects.

These days, this motley crew of experimental drugs is experiencing a renaissance online, but are these drugs legal or safe? And do the people using them even care?

Goop for men

Ipamorelin will help you burn fat. MK-677 will give you bigger muscles. The combination of BPC 157 and TB-500 will speed up injury recovery and has been nicknamed the Wolverine Stack, after the X-Men character known for his superhuman healing abilities. Retractable claws sold separately.

These are the claims you will find in videos made by brawny men who all but claim that injectable peptides are the latest cure-all for the gym crew. They are cast as superior to growth hormone injections, which are accompanied by a laundry list of potential side effects including fluid retention and carpal tunnel syndrome, because you are not adding synthetic growth hormone to your body; you are stimulating your body to naturally produce more of this hormone.

Side effects are reported as anecdotes. Many users talk of an increased appetite. Some worry about the potential for this overstimulation to trigger cancer down the road. The fact that injectable drugs go directly into the blood and bypass the body’s natural defenses against toxic substances makes them riskier in theory than pills. The scientific studies of these experimental drugs were never large enough or long enough to establish a clear safety profile, so all we are left with are vague reassurances from tiny studies and testimonials from YouTubers and TikTokers. An actual internal medicine physician on YouTube leans into the latter quite hard when he says, “Please! Let’s get anecdotes!” He follows this up with, “I think this could be big” and, “I did my research. I watched tons of videos!” And no, he is not being sarcastic, unfortunately.

There is a lot of money to be made in facilitating a hookup between these so-called peptides and curious parties. With the rise of telehealth, you can find a doctor who has bought into the peptide hype and proudly advertises these services. One such telehealth company is rather bold in its publicity: “Weight loss. Fat burning. Faster recovery. It’s the magic solution you didn’t know you needed.” You provide them with basic information. You pay USD 349. You get a consult via phone or video conference. Their partner pharmacy will then ship the experimental drug directly to your door.

The psychology of the peptide space is also worth noting, as it ties into how wellness and body optimization can be gendered. There is something very masculine-coded in the act of injecting yourself with black-market experimental drugs whose names are sterile combinations of letters and numbers, like MK-677 and TB-500, to grow bigger muscles. Goop this is not, at least not in its aesthetic, though a comparison is apt. The host of a YouTube channel called Masculine Medicine says that the peptide ipamorelin gives you better hair health, while another YouTuber endorses peptides as part of a great skincare routine. I found a series of papers all about the alleged dermatological benefits of the peptide GHK. The lead author owns a store called Reverse Skin Aging, which sells these peptides. We are not far from Gwyneth Paltrow’s wellness emporium.

The key, though, to understanding the sensationalism surrounding peptides comes from a criminal defense attorney quoted in a Men’s Health piece about this fad: “Many bodybuilders consider themselves on par with lab rats,” he said. “If they’re hurt now [because of a training injury], they can’t wait for FDA approval.”

Indeed, regulatory agencies are no fans of these peptides. In the United States, the company Warrior Labz SARMS received a warning letter from the Food and Drug Administration (FDA) last summer for selling Merck’s experimental drug, MK-677. The company was labelling it “for research purpose only” and “not for human consumption,” but was clearly intending it for human use. Elsewhere, the FDA warns that the use of these experimental drugs, like BPC 157, GHK, and GHRP-6, in compounded medication—meaning medication that is tailored by a pharmacist to an individual’s special needs—poses a risk for immune reactions. Echoing the scientific literature, they write of ipamorelin that “we lack sufficient information to know whether the drug would cause harm if administered to humans via [injection].” The peptide pralmorelin (or GHRP-2) is clinically approved in Japan, but only as a way to diagnose adults who are deficient in growth hormone.

I reached out to Health Canada to know how these experimental drugs are regulated in this country. I was told that growth hormone secretagogues are subject to the Food and Drugs Act, and if Health Canada has not authorized the sale of a health product, it is illegal for it to be sold in Canada. I searched for many of them through the agency’s Drug Product Database and Licensed Natural Health Products Database and could find none of them. A recall issued by Health Canada in 2019 specifically highlights MK-677 as not being authorized in Canada for any use.

In case you are a competing athlete, you should know that many of these experimental drugs have been banned by the World Anti-Doping Agency (WADA). That BPC 157, originally found in a longer form in stomach juices, was recently banned for being a “non-approved substance,” while the growth hormone secretagogues also feature on WADA’s prohibited list under “peptide hormones, growth factors, related substances, and mimetics.” It can be challenging for laboratories to detect this type of doping, though. Growth hormone-releasing peptides are so poorly studied, we often do not know how they get metabolized in the body and thus which molecules to look for. And the growth hormone whose production they are alleged to increase is natural, making testing even harder.

But just because these substances are banned is no proof that they work. In 2012, Dr. Gerhard Baumann published a critical review on growth hormone doping in sports, paying particular attention to contrasting what athletes believe with what has been demonstrated scientifically. Dr. Baumann is an endocrinologist, now professor emeritus at Northwestern University. He is also a member of the scientific advisory board of Partnership for Clean Competition, a nonprofit founded by major sports organizations and dedicated to protecting the integrity of sport. An important point he made in his paper is that the evidence for even growth hormone itself to be ergogenic, meaning that it would enhance athletic performance, is weak. And when peptides like those endorsed today were tested to see if they would enhance performance by increasing growth hormone secretion, they were shown to be largely ineffective.

Since this 2012 publication, there has been very little new research into this question. Athletes may be using these substances in the belief that they will give them an edge, although how common these illicit practices are is unknown, as they are shrouded in secrecy.

We are thus left with poorly studied experimental drugs referred to as peptides, although some are not, sold for “research use only,” though clearly meant for human consumption, to gain a wide array of physical benefits that are unlikely to manifest. Just because the Liver King injected himself with some of these peptides, it does not mean that they were beneficial in any way. Ironic considering they ended up harming his reputation, at least for a little while.

Take-home message:
- Peptides and assorted experimental drugs, like TB-500 and MK-677, are being recommended by fitness influencers to grow bigger muscles, lose fat, and recover from injuries faster
- These drugs, many of which are claimed to boost levels of growth hormone, were studied in rodents and very small groups of human volunteers before being abandoned for not being beneficial or for causing unacceptable side effects
- They are banned by the World Anti-Doping Agency and appear to be illegal in Canada and the United States, but can be purchased online


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