You’ve just had a seriously sweat-filled workout, and you’re already feeling lighter. You step on the scale, and your suspicions are confirmed — you’ve actually lost a pound! Yes!

This proves sweating helps you lose weight, right? Not exactly.

While you did step on the scale and see that your “weight” has dropped, it’s due to fluid loss, not permanent weight loss. In other words, as soon as you rehydrate (which you should do, stat, especially if you’ve seen a drop in your scale weight since before your workout), your weight will return to the level it was prior to the start of your session. For proper rehydration, the general recommendation is to drink 16–24 ounces of water per pound lost during exercise, which is important because dehydration can cause everything from muscle cramps to dizziness if not addressed quickly.

OK, but doesn’t sweating a lot mean you’re burning more calories, and that will help you lose weight faster?

That isn’t exactly true either. Despite what some brands or products claim, those heated yoga classes or sweat suits won’t help you permanently drop pounds by increasing your sweat level alone. Why not? Your calorie burn isn’t measured by the amount of sweat you shed during a workout but rather by the amount of intensity or effort you put into it. Measuring your heart rate or tracking your perceived exertion level during your workout is a much more accurate way to track your expenditure than by how sweaty you are by the end.

And if you don’t get super soaked during your gym session, don’t “sweat it” either — the amount each individual perspires has to do with the number of sweat glands you were born with. (Most of us have somewhere between 2–4 million of them.) The functions of sweat are to help cool your body and to regulate your temperature, whether you’re rocking it out in cycling class or waiting for the bus on a hot summer day.

So, what does it all boil down to? Sweat is a good thing — it’s your body’s cooling system, but don’t count on using it as your gauge for lasting weight loss. Breaking a sweat (and the amount you perspire) has more to do with your genetics and the temperature of your environment than the intensity of your workout or the amount of calories you are burning. Skip trying to simply sweat off the pounds with saunas and sweat suits. For true, lasting weight loss, instead keep your focus on a consistent, balanced workout plan and a healthy diet with the right caloric deficit.