Sweaty secrets: all you ever wanted to know about perspiration (and a lot that you didn’t!)

If there’s one thing that we all have in common, but hardly ever talk about, it’s that we sweat.

From the glisten on your forehead after a spin class, to clammy hands and damp patches under your armpits before a big meeting, sweating is completely normal.

In fact, the average human sweats around 278 gallons (1,263 litres) every year. Over a lifetime, that’s well over 100,000 litres of perspiration.

“Sweating isn’t a sin and shouldn’t be seen as one. It’s perfectly normal and it’s your body’s way of regulating its core temperature,” says personal trainer Paul Tomkins .

Adding to this, Dr Vijay Nayar at Healthium Clinics says: “Our core temperature may rise due to infection, heat, stress, exercise and sometimes even when we eat spicy food. When this happens, your nervous system then signals the sweat glands to release fluid onto the skin which evaporates and cools us down.”

But despite being a natural process, for a lot of us, sweating is embarrassing. We may even associate it with poor hygiene. Yet the reality is, sweat is far from dirty.

“Sweat is composed of mainly water with some electrolytes such as salt added in,” says Dr Nayar. “Over the course of a day an average person loses around half to one litre at rest but this will increase in hot climates and with exercise.”

So what’s actually going on under your skin when you sweat? Why do some people sweat buckets while others barely break a glow? It’s time for a few sweaty truths…

Discover our full range of health benefit guides and find out what to eat for a workout, what to eat for healthy joints and the best fitness trackers for exercise lovers. Plus, browse our energy-boosting breakfast recipes.

What causes excessive sweating?

Although it’s a normal bodily response, for some people sweating can cross the line from simply inconvenient to excessive.

“Genetics play a significant role, meaning some individuals naturally have more active sweat glands than others,” says Dr Ross Perry, medical director of Cosmedics skin clinics.

“Hormonal changes, such as those experienced during puberty, pregnancy or menopause, can increase sweating; so can stress and anxiety. Body size and composition also influence how much heat the body generates (with people carrying more body weight often producing more heat), while certain medical conditions, such as anxiety or an overactive thyroid gland can affect sweat production.”

Medications, including antidepressants, painkillers, hormone treatments and some blood pressure medications are all known to increase sweating as a side effect too.

Excessive sweating, known as hyperhidrosis, affects around half a million people in the UK. Primary hyperhidrosis tends to be in a localised area, most commonly the armpits, while secondary hyperhidrosis is general, all over sweating, caused by underlying conditions.

"Hyperhidrosis is defined less by the amount of sweat produced and more by its impact on daily life,” says Dr Perry.

“If sweating occurs in situations where it wouldn’t normally be expected, such as in cool environments or at rest, and interferes with work, social interactions or confidence, it may be considered excessive.”

Think you might be suffering from hyperhidrosis? Help is available. “Hyperhidrosis is assessed primarily through a detailed history rather than precise measurement,” says Dr Perry. Your GP may recommend treatments such as prescription antiperspirants, medications and botox, to specialist therapies.

Should sweat smell?

Contrary to what you might think, sweat itself is odour free. Instead, stinky sweat may develop when sweat interacts with bacteria on your skin.

If you’re partial to sitting in sweaty clothes after a workout, you might notice the smell becoming more pungent. The longer sweat sits on the skin, and the more bacteria feed on it, the stronger the odour becomes.

“Some people naturally have stronger-smelling sweat than others, and this is largely due to genetics,” says Dr Perry.

“Differences in the skin’s microbiome – the community of bacteria that live on your skin – as well as the activity of apocrine sweat glands found in areas such as the armpits and groin, play a key role. These glands produce a thicker sweat that bacteria break down more easily, leading to stronger odour.”

The foods you eat can make your sweat stink a little more too. “Garlic, onions, spices and alcohol contain compounds that are excreted through sweat, and broken down by skin bacteria into more pungent by-products. This alters the scent of sweat rather than increasing the amount produced,” says Dr Perry.

So if you’re tucking into garlic-heavy pastas, spicy curries and onion-loaded burgers, then be prepared to feel the heat – and the subsequent smell – a little more.

Does being unfit make you sweat more?

If you’re dripping more than everyone else in the room, don’t panic.

“People who are physically fit tend to start sweating earlier and may sweat more during exercise,” says Dr Perry. “This is because their bodies are better adapted at regulating temperature. Sweating efficiently allows heat to be released more quickly, helping to maintain a stable core temperature.”

With this in mind, increased sweating during exercise can actually be a sign of good cardiovascular fitness rather than a lack of it. So if your gym vest is soaked through, take it as a good thing.

On the other hand, Dr Nayar says that sedentary people may sweat more during everyday activities, such as stair climbing or just carrying the shopping. “This is because their bodies are less efficient at temperature regulation.” Take this as a gentle warning to move more, not less.

If sweat is something you want to minimise, wear loose-fitting T shirts or vests made from sweat-wicking fabrics. Avoid heavy cotton as it can trap heat and moisture.

Can you sweat out a hangover?

After a big night it’s tempting to think that a sweaty workout, sauna session or strong coffee will help to sweat the alcohol out of your system. Unfortunately, that’s not quite how it works.

According to Dr Nayar it’s a myth that you can sweat out a hangover. “Alcohol is metabolised by your liver and sweating will not remove alcohol in any meaningful way.”

That said, you may naturally sweat more after a night of boozing. “Alcohol causes blood vessels to dilate and interferes with your temperature regulation which can increase sweating,” adds Dr Nayar.

Heat only makes things worse, so a coffee is unlikely to make you feel better if you’ve got the hangover sweats. “Hot drinks can have a similar as alcohol effect by raising your internal body temperature, increasing the amount you sweat,” says Dr Nayar.

And if you’re planning on powering through a sweaty workout post-drinking, think again. It could backfire. “It’s going to add to dehydration and further salt loss, making you feel worse quite quickly,” says Paul.

Is it possible not to sweat?

Regardless of how normal sweating is, the truth is that most of us would happily reduce it. In 2019, Prince Andrew famously claimed he was unable to sweat due to a condition known as anhidrosis, which he attributed to high adrenaline levels following the Falklands War. Although this raised eyebrows, the condition itself does exist.

“It is possible not to sweat and there are rare genetic conditions which may cause this,” says Dr Nayar. These include anhidrosis and hypohidrosis (under-sweating); conditions in which the body either produces very little sweat or none at all.

It’s not known exactly how many people suffer from these but nerve damage, certain medications and even genetics can play a role. Keep in mind that under-sweating is no good thing. A body that can’t cool itself down is more vulnerable to heat-related illnesses such as sunstroke.

For most of us antiperspirants are the go-to solution for sweat-zapping. “These work by temporarily blocking sweat ducts, usually with aluminium-based compounds. This then reduces the amount of sweat that reaches the skin,” says Dr Nayar.

“Current evidence suggests that antiperspirants are not harmful or that blocking sweat affects overall temperature regulation. Similarly, there is no strong evidence linking antiperspirants to cancer or Alzheimer’s disease.”

But if you have sensitive skin or experience irritation or allergic reactions it’s best to avoid fragrances, alcohol or aluminium salts. “You may be better off using deodorants rather than antiperspirants,” warns Dr Nayar. These allow sweat but keep the smell under control.

Ultimately, sweat is unglamorous, but it isn’t the enemy and, if anything, proves that your body is working as it should be. Pay attention to it too. It can be a sign you need to move more, adjust your habits or, in some cases, speak to a GP.

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