The complete guide to peptides in bodybuilding

From semaglutide and tirzepatide to BPC-157, MOTS-C and IGF-1 LR3 – why peptides have become one of the most talked-about areas of modern bodybuilding

By Gary Chappell

Peptides in bodybuilding have become one of the most talked-about areas of performance enhancement in recent years. It sometimes feels like no one got shredded or built muscle before they arrived.

Competitors now use them to improve fat loss, recovery, sleep, and overall physique quality, often alongside, or instead of traditional PEDs.

But what exactly are peptides? Do they actually work? And where do newer compounds such as MOTS-C and SLU-PP-332 fit into the picture?

What are peptides?

Peptides are short chains of amino acids that act as signalling molecules in the body. Instead of directly adding hormones like anabolic steroids peptides, depending on the compound, may help stimulate processes linked to:

Release more growth hormone
Repair damaged tissue
Burn fat
Regulate appetite and metabolism

The appeal for bodybuilders to use peptides is clear. Peptides are typically used to:

Boost natural growth hormone (GH) and IGF-1 levels
Enhance fat loss, particularly stubborn and visceral fat
Build and preserve lean muscle through better protein synthesis and recovery
Speed up recovery from workouts and training stress
Accelerate injury healing (tendons, ligaments, muscles, joints)
Improve sleep quality (deeper, more restorative sleep)
Reduce inflammation and joint pain
Strengthen connective tissue
Aid body recomposition (better muscle-to-fat ratio)
Provide anti-aging benefits (skin, hair, energy, and vitality)

Many athletes see peptides as a more targeted option compared to traditional PEDs, particularly for fat loss, recovery and injury management. Human data remains limited and long-term safety profiles are still largely unknown.

The most common peptides in bodybuilding

Fat loss and appetite control peptides

These GLP-1 (and multi-agonist) drugs have transformed contest prep:

Semaglutide (Ozempic / Wegovy)
Tirzepatide (Mounjaro / Zepbound) – dual agonist, very powerful
Retatrutide – triple agonist, one of the most potent weight-loss compounds currently in development

These are the most widely used, but several other compounds are also worth mentioning:

AOD-9604 is also worth a mention. This is an HGH fragment designed specifically for fat breakdown with minimal other effects.

HGH Frag 176-191 is a modified fragment of growth hormone designed specifically to target fat loss with fewer GH-like effects.

Benefits of all: Powerful appetite suppression, easier dieting, significant fat loss, and improved insulin sensitivity. Retatrutide also increases energy expenditure.
Downsides: Muscle flatness if diet isn’t managed, GI side effects and difficulty with carb loading.

Growth hormone secretagogues and direct growth peptides

These increase your body’s own GH output or act downstream:

CJC-1295 (with or without DAC) + Ipamorelin – the most popular stack
Sermorelin
Tesamorelin, especially effective for visceral fat
GHRP-2 / GHRP-6
MK-677 (Ibutamoren) – oral GH secretagogue (not a true peptide but commonly grouped)
IGF-1 LR3 – strongly associated with muscle growth and nutrient partitioning

Potential advantages: Improved recovery, better sleep, fat loss, modest muscle gains and overall recomposition.
Reality check: Milder and slower than pharmaceutical HGH, but very effective when stacked properly.

Recovery and healing peptides

The go-to compounds for injury prevention and repair:

BPC-157 – gut health, tendon/ligament repair, anti-inflammatory
TB-500 (Thymosin Beta-4) – tissue regeneration, flexibility, angiogenesis
GHK-Cu – collagen production, skin healing, anti-aging
PEG-MGF (Pegylated Mechano Growth Factor) – associated with muscle repair and localised recovery, though human evidence remains limited.
DSIP (Delta Sleep-Inducing Peptide) – primarily used to improve sleep quality and recovery.

The famous “Wolverine Stack” (BPC-157 + TB-500) is widely praised for getting athletes back to training faster.

Experimental metabolic compounds and exercise mimetics

This is the so-called cutting-edge shift toward metabolic efficiency:

MOTS-C – mitochondrial-derived peptide that improves cellular energy, fat utilisation and endurance
SLU-PP-332 (SLU-PP-2) – exercise mimetic that activates metabolic pathways similar to endurance training
Follistatin-344 is an experimental compound linked to myostatin inhibition and potential muscle growth enhancement. Extremely limited human data exists.

These compounds focus on optimisation and fat oxidation rather than pure size or hunger suppression. Research into these compounds remains in its early stages, particularly regarding long-term human use.

Do peptides actually work?

Results vary hugely depending on the compound, diet, training, genetics and overall PED use. Some peptides, particularly GLP-1 drugs and GH secretagogues, have substantial real-world feedback behind them. Others remain highly experimental and are driven more by anecdotal reports than robust human research.

Remember, peptides are not magic bullets, but they are excellent tools when combined, as mentioned, with solid training, nutrition and recovery.

This guide reflects the current landscape in bodybuilding as of 2026.

None of the compounds mentioned should be considered risk-free and many remain unapproved for bodybuilding use. Athletes should understand the legal, ethical and health implications before considering any performance-enhancing substance.

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Steroids in Bodybuilding: Is Bodybuilding Too Drug Obsessed?

Neil Andrews says bodybuilding isn’t won with a syringe – but James Llewellin argues modern peptides are changing the game

By Gary Chappell

Bodybuilding drug use has become one of the most debated topics in the sport.

So when new Masters IFBB Pro Neil Andrews talks about drug use in bodybuilding, it carries more weight than most.

This is a man competing with a mechanical heart valve, a story already documented on Frontdouble and one that inevitably changes how he approaches enhancement, risk and longevity.

Now running what he says is just 200mg of testosterone cypionate per week, Andrews has thrown himself into one of the sport’s most sensitive debates: has bodybuilding become too drug-driven?

“This game isn’t won with a syringe”

In a recent Instagram post, Andrews did not hold back. “When did bodybuilding become so drug obsessed?" said the man who, in November last year, won his IFBB Pro Card at the European Masters in Milan.

He then listed what is fast becoming the toolkit of modern prep, before making it clear he used none of these during his last run:

No Retatrutide
No MOTS-C
No HGH
No L-carnitine
No SLU-PP-2

And he said: “Bodybuilding has become heavily drug-driven, no denying that. But let’s get one thing straight. Nothing replaces hard work, consistency and going to those dark places others avoid. No drug, no peptide, no protocol is going to do that for you.

"It won’t build grit. It won’t build discipline. And it won’t carry you through prep when you’re exhausted, flat and questioning everything.

"You know why I stand on that? Because last year I beat guys across multiple shows, federations and internationally running 10 times what I was."

Andrews then delivered his most pertinent point: “This game isn’t won with a syringe.

"It’s won with mindset, execution and who’s willing to suffer longer. Get comfortable being uncomfortable."

For Andrews, the argument is rooted in experience, not theory. And it is a message that cuts directly against the current direction of the sport, where newer compounds and peptides are becoming increasingly mainstream.

Even in commercial gyms across the country, bodybuilders will be asked about performance-enhancing drugs long before diet and training are even at a basic, structured level.

Enter an Olympia voice and the 'peptide rabbit hole'

But the response from former 212 Mr Olympia competitor James Llewellin (above), who is set to return to the stage in the amateur ranks at May's PCA Universe this season, shows just how much the landscape has shifted.

While Llewellin did not disagree with the fundamentals of Andrews' argument, he went on to post a compelling narrative in support of peptides.

Responding directly to Andrews, Llewellin said: "Firstly, incredible conditioning mate and, secondly, until a few months ago I would have said exactly the same.

"In fact I still do. Nothing beats hard work, no drug, no peptide nothing. But when you start to go down the whole peptide rabbit hole, it’s quite remarkable what these signaling peptides can do. And not just performance enhancing.

"Nothing beats gear for muscle gains. Nothing. There isn’t a peptide out there that can really build muscle."

Health vs performance

Llewellin continues: "But there are some incredible peptides that are able to up-regulate metabolism, increase mitochondria function, reverse fatty liver, improve cholesterol, regulate blood sugar, lower blood pressure and decrease body fat.

"Peptides are of huge benefit for not only health but also longevity. The exact opposite of what AAS do to you.

"At 53 years old and with two kids, my health has never been so important to me and using less anabolics and conventional fat burners was always the goal for this “comeback” prep.

"Peptides aren’t hormones, they are amino acids that signal the body to do things better and more efficiently. I’ve been super impressed with them. I’ve never felt so good on prep at this [level of] body fat.

"I feel like I’m [in my] off-season, yet normally I’d be killing myself with 1-1.5 hours of cardio a day with my inflammation through the roof. I’d be moody, quiet and not really present for my family. That’s never a good thing.

"Delve a little into them, Neil, even if it’s just for your health. It can always be tweaked and improved no matter how healthy you are.

"Yes hard work and consistency will never be beaten but, when you combine that with less gear and certain peptides, the results can be pretty amazing."

Two philosophies. One sport

What makes this exchange compelling is that both sides agree on the fundamentals: hard work wins, discipline matters and there is no shortcut

But they diverge on one crucial question: Are modern compounds enhancing the process, or replacing it?

Andrews’ position is shaped by something most competitors never face. Competing with a mechanical heart valve forces a level of restraint and realism that cuts through bodybuilding’s usual bravado.

Llewellin's argument, however, reflects where the sport is heading; less reliance on high-dose anabolic stacks, more interest in metabolic and signalling compounds, greater focus on health markers. Not instead of hard work but alongside it.

This is not a case of right vs wrong, it is a shift. Competitive bodybuilding is no longer just food, training and steroids. It is becoming hormones, peptides, metabolism and health optimisation

And the question now is not whether drugs are part of the sport. It’s how much is too much and what actually matters most?