I first heard about MK-677 in the backroom of a gym that smelled like old chalk, sweat, and secrets. It wasn’t on the supplement shelf or being hyped on a billboard. It was whispered about. ‘Ibutamoren’, someone said quietly, like it was too potent to say out loud.
A guy in his late 40s, built like a boulder, leaned in while we were cooling off after a late lift. “You want to recover like you’re 20 again?” he asked me, handing a bottle with no label—just a barcode and a warning look. That was my introduction to the growth hormone stimulant MK-677.
Originally developed to treat muscle wasting and growth hormone deficiencies, it’s gained traction in fitness circles for its supposed ability to help build muscle, reduce fat, improve sleep, and speed up recovery.
Unlike injecting human growth hormones, MK-677 comes in pill form, making it more appealing—and more dangerously accessible. Like most things in the fitness underground, it wasn’t about what it promised. It was about what might be possible.
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Just a few days after my first introduction to MK-677, a friend texted to tell me he knew a way I could gain 5kg-7kg in two months and that it would be mainly muscle. I replied that it simply wasn’t possible.
From the age of 25, I had spent seven years turning my body into what many would describe as a machine — dense, sculpted, powerful, but not bulky in the traditional sense.
I wasn’t a bodybuilder, exactly, but I was training with precision and an obsession with muscle growth. While some people spend years trying to lose weight to look a certain way, I spent years gaining it.
I’d push myself hard, working out five times a week, a little cardio here and there, but mainly lifting—heavy compound movements like squats, deadlifts, bench press. My diet was decent, not perfect. Chicken, rice, eggs, protein shakes, the usual “clean eating” formula. I even tried intermittent fasting because someone on YouTube said it would “reveal the abs hidden underneath.” It didn’t.
I’d managed to nearly get to my goal weight, but was 5kg off – and no matter what I tried over the years, the scales barely budged.
Then my friend sent me the link to something he had used “first hand” so he could vouch for its authenticity – again the words MK-677 flashed up. His “quick fix”, coupled with the fact that someone had literally handed me a bottle felt like my sign, at the age of 40, to try it.
To be fair, Ibutamoren is everywhere, if you know where to look. From weekend warriors and aging lifters to influencers documenting their “body recomposition” journeys on YouTube, and TikTok, Ibutamorenis riding a biohacking wave.
But the science is murky, the regulation basically nonexistent, and the long-term effects still mostly unknown.
‘People are talking about Ibutamoren like a shortcut for muscle growth or fat loss, especially among newer lifters who want quick progress,’ explains personal trainer and health coach Kevin Rail. ‘The problem is that it is not a supplement you pick up with your protein powder. It is not approved for any use, and a lot of what is sold online comes from places where you cannot be sure what is inside. When you do not know the dose or the purity, the risk goes up fast because your body is the test site.’
Yet, as someone who is a bit of a risk taker, I decided to take the plunge – and I must admit the first few weeks were incredible.
My sleep was deep, like my body was finally getting the rest it always needed, while my appetite went through the roof. With it came fast gains in size and within two weeks I had shot up 2kg. In turn, the amount I was able to lift went up and recovery was faster. I looked pumped.
But then came the water retention. Within days I had a puffy face, swollen ankles. When I looked in the mirror I chose to ignore the visible side effects, as it felt like a mild price to pay.
However, my blood sugar crept up and my hunger got out of control. Eating ‘clean’ became a battle. I didn’t feel unhealthy, but I didn’t feel quite right either.
After eight weeks, I stopped. Immediately my drop in weight was noticeable. I went down 2kg, then 4kg. My sleep issues returned and my joints ached. Even worse, my body softened.
Kevin explains that as MK-677 raises growth hormones and IGF-1, which can add weight and fullness, it ‘pulls on the entire hormone system’.
‘That is why people report big jumps in water retention, sore joints, and appetite swings that make eating feel hard to control. Some describe numbness, tingling, or swelling in hands and feet, and they only connect it later.
‘Concerns about heart health are the most serious because strain on the cardiovascular system is not something you want to trade for a slightly bigger pump,’ he warns. ‘It has been studied in medical trials for specific problems, but it is not approved for regular use outside these settings.’
Dr David McLaughlan is a consultant psychiatrist at the Priory and says they’ve seen ‘a noticeable rise’ in body image concerns among young men.
‘The growing promotion of ibutamoren as a muscle-building or ‘anti-aging’ drug is deeply worrying. It has been banned by the World Anti-Doping Agency, and is not approved for human use,’ he explains.
As co-founder of addictive behaviour change app Curb Health, Dr McLaughlan adds ‘the US Food and Drug Administration (FDA) raised safety concerns, highlighting one clinical trial which was stopped early due to signs of congestive heart failure in patients taking the drug.’
The difference between steroids and MK-677
‘Steroids are versions of testosterone that attach to androgen receptors in muscle and other tissues, which pushes protein synthesis and strength,’ ,’ explains PT Kevin Rail.
‘The results tend to be faster and more obvious, but the trade offs are heavier too: your own testosterone can shut down, cholesterol and blood pressure can worsen, mood can swing, acne can flare, hair loss can speed up if you are prone, and some oral drugs strain the liver.
‘MK-677 creates a signal that tells your brain to release more growth hormone (not testosterone), which then raises IGF-1. People notice bigger appetite and more water weight, sometimes tingling or swelling, because it leans on the growth hormone system and fluid balance. It is not approved for bodybuilding use and it is banned in tested sport.’
Mark* first started taking MK-677 in May 2025 and within three weeks, he noticed a significant uptick in appetite—describing it as ‘eating everything in the fridge.’
‘The hunger came on quickly and intensely, especially within a few hours of taking the pill,’ he tells Metro.
This dramatic increase in food intake coincided with a noticeable weight gain, also of around 2kg. Rather than up his dose in a bid to speed things up even more, as I had, Mark remained steady and over two months continued to see weight gain and a fuller appearance in his muscles.
The hunger stayed strong throughout, which made it easy for the 46-year-old to stay in a caloric surplus.
While Mark has yet to reach his goal weight, he insists the initial results have been promising.
‘I’m definitely committed to staying steady with this for now. The progress might be slow, but it’s consistent, and that’s what matters to me,’ he says.
However, Mark also worries he doesn’t know if he can stop. ‘Honestly, it feels like I’m hooked,’ he admits. ‘I don’t know if I can just stop and still keep these results—it’s become part of my routine.’
Dr McLaughlan adds: ‘Any substance that alters growth hormone levels can affect brain chemistry in unpredictable ways. Without medical supervision, people could be putting themselves at risk of serious and potentially irreversible harm.
‘We urge anyone experiencing issues relating to body image or addiction to speak to a qualified medical professional.’
After taking a two-month break I tried MK-677 again, this time being more careful about how much and coming off it if I didn’t feel so great.
At the moment, the gains are very quick and my body looks full and muscly – but there have been days where I have had pounding headaches, or really powerful stomach cramps.
I also live with the knowledge that MK-677 is not FDA-approved and may carry side effects I’ve yet to encounter, which could be even more dangerous.
So why do I take it? I feel that you only live life once and I want to test my body. At least I can say I did everything I could to obtain the best physique possible.
And there’s no getting away from the fact that people like me are willingly hacking their biology without necessarily waiting for long-term safety data or regulatory approval.
You only have to look at someone like Bryan Johnson, who regularly has stem cell therapy and used immunosuppressants usually given to for organ transplant patients in a bid to live longer, to see how far some people will go.
It feels like a new era where pharmacological self-optimisation is becoming mainstream and the line between medicine and lifestyle enhancement is blurring.
However, MK-677 shows how quickly new science can leap from the lab bench to TikTok-fueled trends, where people happily experiment on themselves.
The question is, are users really prepared for what comes next?
*Name has been changed
PT Kevin Rail is a contributor at Premium Saunas, a company that promotes a lifestyle centered around wellness and relaxation.
