Is it true when you sweat it means your loosing weight??

only if your exercising, but not techniqually. because your only loosing water weight through sweat. and the second you drink something all that water weight goes back on, because you need to replace it

Sweating from exercise does indicate that you are burning calories. The more calories you burn the more heat has to be dissipated. If you are sweating because of high ambient temperatures that doesn’t indicate you are burning calories; you won’t burn more calories in a hot room than a cold one; it is just harder to dissipate the heat you generate exercising.

Exercise alone does not always burn enough calories to guaranty weight loss. For the average person an hour of strenuous exercise may burn 1,000 calories. Consider that a fast food meal an easily contain double this amount of calories so just a couple of extras a day can cancel out the calories you burn exercising.

Exercise can help you loose weight if you are otherwise eating a healthy diet but exercise alone probably often isn’t enough to reach or maintain a healthy weight.