Many folks believe that the harder they sweat the more weight they will lose. So they pile on the clothes, the thick sweat pants so appropriately named, and work on getting sweaty. And yes, in the short term they will lose weight and all that weight will be water weight. Once these fitness fiends replenish their lost fluids and rehydrate themselves the water weight will return. Wearing workout gear that makes you sweat will not help you burn more fat, build more muscle, or spot reduce an area, but they will make you sweat. When working out you don't want to get overheated and dehydrated. Dress in layers so you can peel off clothes as your body warms up and you begin to sweat in your sweats.