Peptides and testosterone therapy have become popular fitness trends over the past year. Experts say these substances may not be what they are being pushed as on social media, and that their effects on young people go beyond just physical. (Image: Rocco Ventra)
By Rocco Ventra & Dallas Reynolds| @rocco.ventra @dallasolivia_
Content Advice: This story discusses body image and suicide.
If someone offered you a drug that promised your dream physique — but you didn’t know what it was, how it was made, where it came from, or what it might do to your body — would you take it?
For thousands of young men scrolling through social media, testosterone and peptides are being marketed as exactly that.
Driving this trend is the rise of biohacking, a social media-fuelled movement that encourages people to use science, technology and self-experimentation to optimise physical and cognitive performance.
Within this culture, concepts such as testosterone-maxxing and looksmaxxing have gained traction.
Merriam-Webster defines looksmaxxing as “efforts, sometimes extreme, that young men take to look more attractive.”
Testosterone-maxxing promotes increasing testosterone through strict diets, intense exercise, and synthetic interventions such as testosterone replacement therapy (TRT).
Together, these trends reflect a broader online culture centred on maximising appearance and performance — often through increasingly intensive interventions.
That interest is growing.
According to Google Trends, Australian searches for “peptides”, “Australia peptides” and “what are peptides” have risen over the past year, while searches for “testosterone therapy” reached an all-time high in April 2026.
Search term: peptide
Search term: testosterone therapy
Graphs displaying the rising interest in the search terms “peptide” and “testosterone therapy” (Images: Dallas Reynolds & Rocco Ventra)
What are peptides and testosterone?
Peptides are short strings of amino acids that naturally occur in the human body. The order in which these amino acids join dictates the peptide’s function.
Peptides have a wide range of functions; bioactive peptides benefit the human body.
One example is insulin: a peptide used by people with diabetes to regulate blood glucose levels.
The peptides pushed by social media influencers are typically synthetic peptides, which are peptides engineered in laboratories to mimic their natural counterparts.
Testosterone, meanwhile, is the body’s primary male sex hormone.
It plays a central role in muscle growth, bone density, red blood cell production, libido, fertility, and the development and maintenance of male secondary sexual characteristics.
TRT is a prescription treatment used to restore testosterone to normal physiological levels in people diagnosed with hypogonadism — a medical condition in which the body does not produce enough testosterone.
In Australia, hypogonadism is estimated to affect around five in every 1,000 men.
Financial incentives
Most influencers guide their audience to purchase peptides by instructing them to go to their social media bio and use their affiliate link, a URL assigned to a marketer that tracks traffic and purchases sent to a brand’s product or service.
The affiliate link leads to the online peptide seller affiliated with the influencer.
Joseph Mencel is a bodybuilder who has earned International Federation of Bodybuilding and Fitness (IFBB) Professional status.
He is also the first Australian Men’s Physique Professional to compete at both the Pittsburgh Pro and New York Pro IFBB bodybuilding competitions.
Mencel runs an Instagram page with over 50,000 followers where he posts a mixture of business and fitness content.
He says that influencers are “financially motivated” to push peptides on their pages.
“I think a lot of influencers do things to get attention. It’s like, ‘How do I get the most views? How do I get the most likes? How do I get the most shares?’ I think that ties into a lot of influencers wanting to talk about peptides because they know that the attention is there,” he says.
Synthetic peptides and scientific credibility
Dr Andrew Abell is a chemistry professor at Adelaide University who has conducted research into the synthesis and use of peptide mimics as new therapeutics for diseases, cancer, and infections.
He is also an Associate Investigator at the Australian Research Council Centre of Excellence for Innovations in Peptides and Protein Science.
“A lot of them are just trying to make a profit, and the classic way of people dealing with this as influencers and whatever is to put a few scientific names next to things to try and give them some credibility,” Abell says.
Abell says consumers should be cautious about buying peptide products online.
“I would not trust any products from someone who does not have a serious background or serious capability in that area,” he says.
“As a chemist, if you synthesise something in a laboratory, you have to do rigorous, detailed chemical analysis to confirm what you’ve got and to confirm its purity.
“It’s one thing to get a sample to use for research purposes. To put something in a human, you’ve got to have serious protocols in place to confirm what you’ve got. I wouldn’t go near anyone unless they’ve got those protocols available and published, and evidence of them.”
Dr Ian Musgrave is a molecular pharmacologist at Adelaide University who conducts research with peptides.
He says that the lack of human clinical trials on synthetic peptides is an issue.
“For example, BPC-157 [a peptide], there’s some work in animals showing effects, but the only human legal trial for that was abandoned without reporting, which is a little bit suspicious,” he says.
“GHK-Cu [is] a small … tripeptide. There’s good evidence, as a topical cream, it’s good for certain dermatological indications, but there’s no evidence that, as an injectable peptide, it’s actually effective in humans.”
The unregulated supply chain
According to extended care paramedic and gym owner Patrick Miller, supply chains have shifted outside medical oversight.
He says most young men in South Australia are getting their testosterone from other gym-goers to help change body composition, put on more muscle and reduce fat.
“Generally, it comes through the black market, through similar sorts of avenues of people who are importing illicit drugs, [like] drug dealers and bikies,” he says.
“They’ll bring the testosterone in, and then they will give it to people who sell it in gyms.
“Somebody who is using it themselves will generally promote it in the gym, and then they’ll be selling it second-hand through these people who are importing it.
“When you’re in commercial gyms… I would say you’re probably getting closer to maybe 20 to 25 per cent of the young people in there [taking] testosterone — it’s becoming quite prevalent.”
Physical and psychological effects on users
A 2025 study by researchers from Griffith University and PEDTest Australia analysed illicit testosterone and other anabolic-androgenic steroid products sold in Australia and found widespread issues with quality and safety.
More than half of the 28 samples tested were mislabelled or mis-sold, and several testosterone products contained different compounds than those listed on the label or significantly different dosages than advertised.
Heavy metals, including lead, cadmium, and arsenic, were also detected in injectable testosterone products, highlighting contamination risks within unregulated supply chains.
According to UNSW Sydney, unsupervised use of these substances can result in infection, organ damage or death, with contaminated products linked to toxic metal poisoning, heart attack, stroke and organ failure.
From Miller’s own experience, he’s seen users develop severe acne from testosterone use, alongside an increase in mood swings.
“They become angry and intolerant with things that they would normally find easy to deal with,” he says.
“With the extra testosterone, they’ll be almost elevated and feeling better.
“And then when it stops, there’s this period where they have a real lull in their mental health.”
Miller partially attributes the rise in testosterone-maxxing to the biohacking community, where he says there is a “big push for men post-30 to start taking supplemental testosterone in some form.”
Regulation and legal status in Australia
According to the Therapeutic Goods Administration, the Poisons Standard 2026 contains the classifications of medicines and poisons into schedules for inclusion in the relevant legislation of the states and territories.
Under the standard, peptides and testosterone fall under Schedule 4, which lists prescription-only medicines.
Musgrave says items in Schedule 4 are classified by balancing their potential for harm against their potential for benefit.
This means that peptides and testosterone, unapproved by the TGA, can still be accessed by people who want to use them if a doctor is willing to write them a prescription.
However, there are multiple exceptions.
One of these is that unapproved peptide products that “are not clearly labelled, including products identified only by codes, or those that do not clearly state the active ingredient, strength or dosage, pose significant safety risks” cannot be assessed for lawful importation under the Personal Importation Scheme.
While being marketed for recreational use, online peptide shops often have disclaimers on their site claiming that their products are for research purposes only.
An example of a disclaimer on an online peptide shop. Source: American Research Labs
Either that, or these disclaimers make it clear that they market their products to laboratories, researchers, or academic institutions.
Why young men are turning to chemical masculinity
For Nick*, 35, the process of obtaining TRT was extremely cheap and easy.
“If you don’t have it prescribed… you can go… to just about any gym, and you could find someone who’s got it or is willing to sell it,” he says.
“I had heaps of mates [who] have been on it forever. They all had the hookups…. so, I just asked one of them and got it within a couple of weeks.”
Over six months, Nick took 250 milligrams per week of injectable “Test E”, short for testosterone enanthate.
Nick says the most common misconception about TRT is that it is only used by gym-focused “meatheads”.
“A lot of guys are just taking it to make themselves feel better. They’re self-medicating, really… and get addicted to the results,” Nick says.
He estimates that about one in five of his friends either are currently on testosterone or have taken it.
When asked whether he would go on TRT again, Nick doesn’t hesitate.
“Definitely,” he says.
“A lot of people are turning to it… the results are infinitely better than getting the natural supplement.
“I’m not big on the whole looksmaxxing thing. I understand everyone wants to look good and be attractive. That’s just basic human nature.
“But it’s also kind of disappointing… when we’re all messing with our bodies.”
“There’s a lot of talk in the media about the pressures placed on women to look good and what you’re sort of supposed to look like,” he says.
“Men, everyone seems to forget, especially young men…. we’re also prone to it too. There is that societal pressure to look amazing.”
Adelaide University student Cori* injected peptides after seeing them on his TikTok For You page, which features recommended content for him.
“My whole For You page was just peptides, peptides, people blasting substances. It kind of steered from steroids to peptides, so then it was always on my feed, so I was always curious,” he says.
One of Cori’s needles and a vial containing retatrutide. (Image: Rocco Ventra)
Cori injected himself with retatrutide and GHK-Cu: two peptides he says were meant to help him lose weight faster and clear up his skin, respectively.
He injected retatrutide in three-to-four-day intervals over a period of three months.
He injected three milligrams of GHK-Cu every day for “maybe a month and a half”.
Over this period, Cori says he lost “around 15 kilos” and that his appetite “completely disappeared”.
Cori on his first time taking peptides.
The pressure to indulge: social media’s influence on body-image and masculinity norms
The BodyKind Youth Survey conducted by the Butterfly Foundation found 53.8 per cent of respondents aged 12 to18 years reported being dissatisfied with how their body looks.
Two in five reported never or rarely feeling good about their body.
Around 75.5 per cent of young people wished they were thinner or leaner, while 66.6 per cent wished they were more muscular.
Dr Alissa Knight is a clinical psychologist and researcher. She says clients are “constantly” telling her of their use of substances to achieve their dream looks.
Clinical Psychologist Alissa Knight. (Image: Rocco Ventra)
“I would say on average in the last six months … I would have at least two out of my five [clients] every day bring up to me an idea of either going on it or wanting to go on it. GLP-1 injections, Ozempic, male steroids … they don’t seem to have any kind of care or worry about the side effects,” she says.
She has also seen the worst effects body dissatisfaction can have on young people.
“It causes chronic anxiety, agoraphobia, which is like [being] housebound. I feel like I’m so not perfect, I’m ugly, I’m so not right, I won’t even step out in public,” she says.
“I’ve seen people crippled from that for years. 12 years locked in their home because they’re so fixated on their body image.”
According to the BodyKind Youth Survey, 57.2 per cent of respondents said social media contributed to them feeling dissatisfied about their bodies. Seven in 10 respondents thought that media and social media platforms need to do more to help young people have a more positive body image.
Dr John Mingoia is a behavioural science researcher and a member of Adelaide University’s Behaviour-Brain-Body research centre.
Mingoia says digital environments and the people within them create “norms” which dictate your personal standards through a process called internalisation.
“It’ll be influencers if you’re talking about social media … that [are] basically creating your set of rules for what it means to be attractive,” he says.
“Internalisation basically means that, cognitively, they set that as a personal standard for themselves … constantly judging themselves and everybody else against that standard. Well, this is what everyone’s agreed upon as attractive. If I don’t meet that shape, I’m not attractive.”
Knight has seen the effects of social media on her clients and the extremes they can lead to:
Alissa Knight discusses the effect social media has had on her clients.
University student Cori, who says he will continue to use peptides, is not concerned about the potential consequences.
“If something bad happens, something bad happens, I’ll suffer the consequences,” Cori says.
*Names changed for anonymity
If you or someone you know needs help, contact:
Health Direct: 1800 650 890
Butterfly Foundation National Helpline: 1800 33 4673
National Eating Disorders Collaboration Body Image Resources
Beyond Blue: 1300 22 4636
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