If you've been wondering whether your activewear is actually healthy, you're not alone. Recent headlines have sparked conversations about polyester, PFAS and plastic-based clothing. While research is still evolving, many scientists are investigating how synthetic fabrics and the chemicals used to make them impact both our health and the environment. After learning more, I decided to make the switch to natural fibre activewear, and I won’t go back.

Key Takeaways

• Most activewear is made from plastic-based fibres like polyester and nylon.
• Scientists are investigating the health impacts of chemicals used in some synthetic textiles, including PFAS, BPA and other endocrine-disrupting compounds.
• Hemp is a very durable, breathable, lower-impact alternative that performs surprisingly well.
• You don't need to throw everything away. Reduce daily wear and replace items when the time comes.
• I bought and tested hemp activewear myself before ever contacting the brand. Here are my questions and experience.

Is Activewear Really Made From Plastic?

Like many people, I'd spent years living in activewear. Leggings weren't just for work outs; they were my work uniform, my weekend clothes, my travel outfit... basically everything.

I loved how comfortable they were, but an article back in 2023 about alarming BPA levels in sport bras made me rethink what I was wearing. I didn't realise that most activewear is made from plastic, and even less that the chemicals in plastic clothing or their coating could be an issue…

Polyester, nylon, polyamide, acrylic,... These are all synthetic fibres created from petroleum, engineered to be stretchy, lightweight and durable, which is exactly why they've become the standard for sportswear. Then there's elastane (also called spandex or Lycra), which gives leggings their stretch.

So about 3 years ago, when I realised that I was essentially wearing plastic against my skin, I started to only wear my activewear when I did my work outs.

Why Is Everyone Talking About Polyester Right Now?

You would have seen activewear popping up in the news recently, particularly surrounding brands like Lululemon.

The headlines centre around investigations and lawsuits relating to PFAS, often called "forever chemicals" because they break down incredibly slowly in both our bodies and the environment.

These legal matters are still ongoing, but the positive news is that they've opened a much bigger conversation about the chemicals used throughout the textile industry. It's not just about the PFAS, it is about the plastic chemicals in polyester clothing.

For many people, it was the first time they'd stopped to ask “what exactly is in my clothes”? Because while we often think carefully about the food we eat or the skincare we apply, we rarely think about what we're wearing for 10 or 12 hours every day.

Especially when we're sweating.

My Journey From Loving Activewear to Questioning It

A few years ago, I gave a sustainability talk for a huge activewear company, and as payment, they gave me activewear. I loved it! I practically lived in those leggings, I wore them to work, around the house, while travelling and running errands, not just for exercise. I just didn't question it that much.

But like all of us, I kept learning. The more I read about plastics and the chemicals associated with synthetic fabrics, the more uncomfortable I became with the idea of wearing them against my skin every day.

A couple of studies impacted me a lot.

1. One study found that male dogs wearing polyester underwear for two years had lower sperm counts, reduced sperm motility and changes to testicular tissue, with most recovering after the polyester was removed.
2. Another study found that female dogs wearing polyester-containing underwear had lower progesterone levels and struggled to conceive, with fertility returning once the garments were removed.

While I know these are animal studies and don't prove the same effects will happen in humans, they were enough to make me question whether I wanted to continue wearing plastic-based clothing.

Our skin isn't an impenetrable barrier. It's designed to absorb certain substances, which is exactly why patches and some medications work through the skin.

I didn't stop wearing activewear overnight. First, I stopped wearing it casually and only wore it when I exercised. Eventually, years later, I decided I wanted to make the change, so I started researching brands, reading reviews and looking for natural alternatives that could still perform.

When I finally made the switch, I donated my old activewear rather than throwing it away. There was nothing wrong with it, and I hoped someone else could continue using it while I chose clothing that better aligned with my values.

Why Are Scientists Now Increasingly Concerned About Polyester?

Scientists are (finally) taking a closer look at the chemicals associated with synthetic textiles and what happens when these fabrics are worn against our skin every day.

While polyester itself isn't considered an endocrine disruptor, many synthetic fabrics have been found to contain or be treated with chemicals such as PFAS (per- and polyfluoroalkyl substances) and BPA (bisphenol A), two well-known endocrine-disrupting chemicals that have been linked to hormonal, reproductive and developmental effects.

One reason for growing concern is that these chemicals can be absorbed through the skin.

1. BPA has long been shown to penetrate human skin and enter the bloodstream.
2. More recently, a 2024 study using laboratory-grown human skin models found that 15 out of 17 PFAS tested were able to pass through the skin, with some short-chain PFAS showing particularly high absorption. Even when absorption was lower, a significant amount of PFAS remained trapped within the skin, suggesting it could continue to diffuse into the body over time.

PFAS, used in some stain-resistant and water-resistant textiles, are among the most widely studied. These chemicals have been linked in research to concerns around immune function, fertility, thyroid health and some cancers, although exposure comes from many sources, not clothing alone.

Scientists found that when fabrics are worn for long periods or under conditions of heat, sweat and friction may increase the release and absorption of these chemicals, contributing to our overall chemical burden.

Although researchers are still studying the long-term health implications, the evidence has grown strong enough that dermal exposure is now recognised as an important pathway for chemicals such as BPA and certain PFAS. This is why there is increasing interest in understanding what our clothing is made from and how the chemicals used in textile manufacturing may affect human health over time.

Another concern is microplastics. Every time synthetic clothing is washed, tiny plastic fibres are released into waterways.

Some studies also suggest that synthetic textiles may release particles into the air while we wear them, contributing to the microplastics we're exposed to every day.

Research is still evolving, but reducing unnecessary exposure to plastics and persistent chemicals where practical is a sensible step many people are choosing to take.

So … Organic Cotton or Hemp?

Organic cotton is a great option, and it's still one of my favourite natural fibres. But for activewear, hemp has a few advantages.

Hemp	Organic Cotton
Extremely durable	Softer but generally wears faster
Naturally breathable	Breathable but can hold more moisture
Naturally odour resistant	Less naturally odour resistant
Requires less water	Uses more water than hemp (although far less than conventional cotton)
Naturally pest resistant	Organic farming avoids synthetic pesticides but still requires more resources
Helps improve soil health	Better than conventional cotton but doesn't regenerate soil in the same way

Organic cotton is definitely a step up from conventional cotton, which often relies heavily on pesticides and huge amounts of water. But to me, hemp stood out as the better material for activewear because I wanted something extremely durable. Hemp is one of the strongest natural fibres in the world. It's naturally breathable, durable, moisture-wicking and odour-resistant, making it incredibly well suited to movement. Unlike polyester, it's also plant-based, biodegradable and doesn't shed microplastics every time you wash it.

From an environmental perspective, hemp is impressive too. It usually requires much less water than cotton, grows quickly, naturally suppresses weeds, needs very few to no pesticides and even helps improve soil health as it grows. So I landed on a brand called Zone by Lydia.

I was worried natural fabrics would stretch, lose their shape, feel heavy or simply not perform well enough for exercise. I couldn't have been more wrong.

My honest ZONE by Lydia review

I also want to be completely transparent about this review. When I ordered these leggings, I hadn't spoken to the company. I didn't ask for a discount. I didn't introduce myself. I didn't want special treatment or to be influenced in any way.

I wanted the exact same experience any customer would have.

I had four concerns before buying natural-fibre activewear.

1. Would it hold and support me?

I was blown away. The fabric feels extremely sturdy, sits securely around my waist and bust, supporting me well when moving and running. 

2. Would the leggings slide down?

The opposite. They stay high and in place when I move. Some of my old plastic-heavy leggings slipped down more.

3. Would they be see-through? 

I would give the opacity a 9 out of 10. If I stretch hard and look very closely, I can see a little, but I have experienced the same with synthetic leggings. I chose the smaller of two possible sizes for me, so if opacity is your main concern and you're between sizes, I would personally advice the larger size so the fabric is under less stretch.

4. Would they be comfortable enough to live in?

Absolutely. They give me back the ease of activewear without being overwhelmingly synthetic.

And I love the clean front. There is no crotch seam running straight up the front and getting involved in places it has no business being. It lies flat, feels comfortable and looks beautiful.

The fits and colours are gorgeous! I'm absolutely loving it.

But Isn't Hemp Activewear Still Made With Some Plastic?

Yes, and most “natural fibre” activewear is.

To give you an example. The leggings I chose from Zone by Lydia are made from 52% hemp, 43% organic cotton and 5% spandex to provide stretch and recovery.

Of course I would love that number to be zero, but compared with conventional leggings that are often 80–100% synthetic fibres, reducing that plastic content to around 5% feels like huge progress.

Is It Worth Replacing All Your Activewear?

At Go For Zero, we don't believe sustainability means throwing perfectly good things away. If your leggings are still in great condition, keep wearing them until they're no longer fit for purpose. That's exactly what I did. I just stopped wearing mine every day, then donated them instead of sending them to landfill.

But when it is time to replace something, that's where we have an opportunity to choose differently.

My Final Verdict

A few years ago, I happily lived in polyester leggings because I didn't know any different, but today, I know more. Scientists are speaking up, research is pointing in a certain direction, so I've chosen differently and didn't expect to love these as much as I do.

Changing something you've worn a lot isn't easy. I expected compromise or for them to be "good enough.” However, I found hemp activewear that is supportive, comfortable, beautifully made and does what it needs to do.

And more importantly, I have the peace of mind of knowing I'm reducing the amount of plastic I'm wearing against my skin.

Is it perfect? No. There's still a small amount of elastane, but compared with conventional activewear, it feels like a huge step in the right direction. And that's exactly what Go For Zero has always been about. Not perfection, but progress.

If you're curious about making the switch yourself, I recommend having a look at Zone by Lydia. I became an affiliate only after buying, testing and falling in love with their products as a customer first. If you decide to purchase through my affiliate link or use my discount code (ELIEN15%), it helps support Go For Zero and the research we do and you receive a 15% discount!

Lots of love,

Ellie x

Frequently Asked Questions

Is polyester activewear bad for you?

Polyester itself isn't classified as "bad," but researchers are investigating the potential health impacts of chemicals used in some synthetic textiles, including PFAS and endocrine-disrupting compounds. Many people choose natural fibres to reduce unnecessary chemical and plastic exposure.

What is polyester made from?

Polyester is a synthetic fibre made from petroleum, meaning it's a type of plastic that's been engineered into fabric.

Why is hemp considered better than polyester?

Hemp is a natural plant fibre that is breathable, durable, biodegradable and doesn't shed microplastics during washing. It also generally requires less water and fewer pesticides than many other textile crops.

Is hemp better than organic cotton?

Both are great natural choices. Hemp is typically more durable, more water-efficient and naturally resistant to odours, making it particularly well suited to activewear.

Should I throw away my polyester activewear?

No. At Go For Zero, we always encourage using what you already own. When it's time to replace your activewear, consider choosing a lower-plastic alternative instead.

Final Thoughts

The biggest lesson I've learnt on my sustainability journey is that every choice doesn't have to be perfect. We simply have to keep learning.