Peptides may accelerate muscle growth, but are they worth the risk?

A decade ago, fitness coach Stephen Arnold would never have told me he was taking peptides.

"People were coy about disclosing their exact 'supplement stack' then. In 2017 it's much more acceptable to be using supplements beyond protein powder and creatine… Bodybuilders and recreational gym enthusiasts are quite open about it."

Arnold, 35, from Perth, is one of a small but apparently growing number of gym-goers taking peptides to help accelerate muscle growth.

Within two weeks, he'd seen his weight increase by two kilograms, despite being in calorie deficit. The biggest benefit for him is simple. "They offer less long- and short-term side effects than the more aggressive steroid."

What are they?

There are various different types of peptides. When you look at the online stores offering them, they promise the earth: safe tanning, fat burning, muscle building, mood enhancing, anti-aging, regeneration.  

Associate Professor Peter Crack from the University of Melbourne has a PhD in peptide chemistry. I asked him specifically about the kind being used as gym supplements.

"These peptides are being used as derivatives of human growth hormones. Broadly speaking, a peptide is a sequence of amino acids, recognised by a specific receptor which then creates an effect."

For gym goers, that effect can be similar to steroids.

"Peptides are drugs that can work in the same way as anabolic steroids so I consider them very similar," Crack says.


There is, however, one major difference: unless you're a professional sportsperson, like Lance Armstrong, peptides are entirely legal.

"Quite a few doctors I know are on them"

Django Nathan, a medical doctor with a degree in molecular biology and genetics, takes peptides because of his busy lifestyle: "Quite a few doctors I know are using them because they have so many beneficial effects and so few side effects. We're not elite athletes – we live rushed lives that can involve 70 hour weeks so staying fit and getting good sleep is essential – and peptides aid that."

The process for getting them is relatively simple, he says.

"You enquire online, then receive a call from the doctor who asks about your medical history and ensures you know the risks and benefits, then a script is sent to a pharmacy that prepares the medication, before they're delivered."

Risks and side effects

Dr Nathan, who is taking Ipamorelin, concedes "only small clinical human trials" have been undertaken, but maintains the risk factor is low.

"Short courses are advised, but the risks of Ipamorelin are minimal, explains Nathan.

"It works on the same pathway as your body's natural growth hormone; there are no links to causing cancer. It's flagged by anti-doping bodies as a performance enhancer, but that's not a worry for people who aren't elite athletes. No big pharmaceutical companies are doing clinical trials though, so long term effects are as yet unknown."

In terms of side effects, Stephen Arnold says: "There can be a few such as increased hunger, increased cortisol, increased blood pressure and water retention. But if used sensibly, these should be very minimal – or even avoided completely."

And they beat protein shakes. "Peptides, being a shorter amino acid chain than protein, get absorbed quicker and bypass the liver, allowing for a greater stimulus than a protein shake."

Which type to take

Ipomarelin, which Dr Nathan is taking, is ideal for those who want to get built.

"Since taking it, I've noticed the size of my muscles increase, despite a decrease in gym time," he states.

Explaining the science behind, Nathan says "it causes hypertrophy (increase in size of muscle cells) and hyperplasia (increase number of cells). It increases number of muscle cells as a downstream effect. Fat cells are also releasing their fat and getting smaller, but it doesn't necessarily mean you'll gain/lose weight."

A common combination is Ipomarelin with Sarms, to balance body building properties with lean muscle mass.

"The product I've been trialling is classed as a Sarms which is a peptide 2.0," says Arnold.

"It's digested orally and, taken properly, has no side effects but does need to be cycled on, normally 12 weeks on, two weeks off."

Altogether, his peptide combination is costing him $280 per month.

The critics

Group fitness trainer Cameron Falloon is skeptical about peptides as a way of getting built or ripped.

"Rather than investing your time, energy and money on peptides, a well designed, personalised, progressive training program in combination with a balanced, nutritional diet will support optimal gains in performance."

The University of Melbourne's Professor Peter Crack is especially suspicious of the many online peptide ordering services available.

"If you're buying online, you don't know what you're getting," he cautions.

"There are always risks to taking drugs off-label. And will these gym-goers turn out like the people in the marketing pictures? I think that's unlikely."

A last resort

But the most interesting word of caution comes from peptide-using Arnold himself: "The costs outweigh the benefits."

Peptides, he says, are a last resort.

"The best long-term results come from balancing biology. Focus on all other factors first: sleep quality/length, stress levels, nutrition, periodised training, work-out supplements, meal timing/frequency, nutrient source. Focus on these before even considering anything else."  

"I'd always encourage young athletes to reach their absolute physical ceiling of potential before turning to peptides or steroids."

Have you seen positive or negative results on peptides? Share your thoughts on them in the comments section below.