Does Sweating More Mean That You Are Losing Weight?

This is a tricky one, because it’s a no, but also a yes... but indirectly. I’m pretty sure that sentence made no sense but let me explain.

First I want to explain the mechanism of sweating. Sweating is the body's mechanism to cool itself down. Your nervous system automatically triggers your sweat glands when your body temperature rises. I found a really good explanation on by

“We sweat when we exercise because our body temperature increases. Sweating or perspiring is the thermoregulation process by which we dissipate, or get rid of excess body heat. As the body gets warmer, receptors in the skin send information to the hypothalamus in the brain which then activates our sweat glands. The sweat glands produce fluid, mainly water and some dissolved solids, that appears on the skin. This fluid then evaporates, taking away some heat as it does, creating a cooling effect on the body.” -

Let me explain the yes component of this answer. You will lose ‘weight’ on the scale after a session (if you sweated a lot), purely due to losing water weight through sweat! But as soon as you rehydrate, the weight will be back.

You can lose approximately 1L of sweat per hour of moderate exercise. A litre of water weighs approx 500g therefore it is possible to lose 500g of weight per hour of exercise. As I said though, this is water weight, which will be quickly gained back once you rehydrate.

The second reason is that in general, if you’re sweating during a session, you’re most probably doing a high intensity workout (not including training in hot weather). This means more calories burnt, and if you’re dieting, and in a calorie deficit, this will equate to a larger deficit which means more fat loss.

This isn’t the whole story though, if you’re sitting on a beach chair on the beach sweating up a storm while sitting there are you burning loads of calories? Urm nope! 

I know I just said that if you’re sweating you’re more likely doing a high intensity workout. But that’s not the be all and end all; some people don’t sweat because of genetics or their body weight, but that doesn't mean they aren’t working super hard during their workout. 

What I’m trying to say is, don’t gauge how hard you’re working by how much you sweat. If you’re exercising, you are burning calories regardless of how much you sweat or not. Sweat during exercise is not a good indication of how many calories you have burnt. You could be exercising in the cold and not sweat at all but it doesn’t mean it wasn’t a good workout. Sweating is just an indication of how hot you have gotten during that session. Ever walked down the road when it’s 40 degrees celsius outside? Pretty sure you aren’t burning a tonne of calories!

In conclusion, wearing a jumper while you’re running on the treadmill (because you think sweating will mean more fat loss) isn’t going to burn more fat than if you were wearing a singlet. 

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