Does Sweating Burn Fat? The Truth Behind the Myth

Years ago, when I worked in the low-voltage systems industry, I remember seeing a small framed plaque sitting on someone’s desk while we were installing a system. It simply read:

“Sweat is just your fat crying.”

For some reason, it stuck with me. I can still picture the desk and exactly where that little plaque sat, even though I couldn’t tell you the name of the company or where the office even was.

It came back to me recently because over the past few weeks, several people at the gym have made similar comments while I’ve been dripping with sweat mid-workout.

It was comments such as you must be having such a great workout, I need to workout like you or you must be burning loads of fat. Apparently, sweating buckets has become the universal sign of a good workout and weight loss.

The worrying part is that they are saying that they aren’t working hard enough simply because they weren’t sweating as much as I was and more so that they think they would burn more fat by sweating more.

The problem is that sweating simply doesn’t work like that.

Sweat isn’t body fat leaving your body. It isn’t your fat crying. It isn’t even a reliable measure of how hard you’ve worked.

Its primary purpose is to regulate your body temperature.

When your core temperature rises, whether from exercise, hot weather or both, your brain tells your sweat glands to release water and salts onto your skin. As that sweat evaporates, it removes heat from your body, helping to cool you down. It’s your body’s natural cooling system.

That’s all it’s doing.

If you step on the scales after a workout and you’re lighter, it’s because you’ve lost water, not body fat. Once you rehydrate, that weight comes straight back because it was only water that left your body.

For me, this is just normal.

I’ve always run hot and I’ve always sweated more than most people, especially during the summer. With the hot weather we’ve been having here in the UK recently, that’s become even more noticeable, which is probably why I’ve had the same conversation several times at the gym over the last few weeks.

If anyone is looking at me as the benchmark for how hard they should be training because of my sweat, they’re comparing themselves to the wrong thing.

The amount I sweat says far more about how my body regulates its temperature than it does about the quality of my workout. Don’t get me wrong, I may be having a great workout, but it’s not the sweat that should be the proof.

Don’t use sweat as your measure of a good workout. Your workout wasn’t ineffective because you didn’t finish looking like you’d jumped into a swimming pool. Likewise, someone dripping in sweat isn’t automatically burning more fat than the person next to them.

Fat loss still comes down to maintaining a calorie deficit over time. Sweat doesn’t change that. Now, can working harder make you sweat more? Of course.

Generally, the harder you work, the more your core body temperature rises, so your body often needs to produce more sweat to cool itself down. But that’s simply your body’s cooling system, not burning fat. High intensity training or cardio will do that for most people, while for me a good weight lifting workout will do the same. During some of my best workouts, I have sweated less. 

Incidentally, by changing my diet, I’ve actually lost around 10 kg over the last couple of months for a couple of medical reasons. Part of me hoped that carrying less body weight might also mean I’d sweat a bit less during what we knew was going to be a particularly hot summer. So far, it hasn’t made much difference. I still sweat just as much.

The reality is that some people simply sweat more than others. However, if you suddenly find yourself sweating significantly more than usual for no obvious reason, or excessive sweating becomes a regular problem, it’s worth speaking to your doctor as there can sometimes be an underlying medical cause.

Otherwise, the next time you leave the gym without your T-shirt completely soaked, don’t think you’ve somehow had a worse workout than the person who did.

And if you happen to be the person dripping in sweat, don’t assume you’ve burned more fat either.

Sweat isn’t your fat crying. It’s simply your body regulating its temperature how it is supposed to.