Liz Neporent, MA
It's not only a bad idea, it's a misguided one: When you pile on excessive amounts of workout clothing for a bigger sweat, you might see the needle on the scale go down immediately after your workout, but the loss is pure water, not fat. The moment you gulp down some liquids, you'll replace your body's water, and the weight will not-so-magically reappear.

Besides, overdressing for exercise is dangerous, especially in hot weather or in a room with poor air circulation. It invites dehydration, and in extreme cases you can put your health at serious risk. You're really asking for trouble if you wear plastic or rubber clothing to maximize the waterworks like Martin Lawrence did. He shed so much water he passed out and was in a coma for three days. People dying in similar circumstances isn't unheard of. And don't even think about wearing a "sweat" suit when you sit in a steam room or sauna.