You lose salt. Shouldnt be a problem for most with normal diets, but if you train like a marathon runner and dont replenish your salt that can lead to problems.
I think it's bollocks. The only thing you lose more of is sweat (water), not fat. Therefore you're just making yourself weaker and more uncomfortable during the workout, only to put the weight back on as soon as you have a drink or two. It's a **** idea unless you're struggling to drop a couple of pounds last minute.
Thanks for the answers. Just wanted to get it clear. The heaters also be fully on in our gym Pretty crazy i think LoL
that's ridiculous. Be sure to drink plently of water before you get there and rehydrate when you leave. There's no reason to sweat out a bunch of water on a daily basis like that. Those suit should only be if used if you are desperate to make wieght in a short amount of time.