It depends on what you want to use 'em for.If it's short-term weight loss, like to make weight for a sport, then it's alright. However, they will not help you lose 10 pounds in permanent weight because it's water loss not fat loss.
If anything they're good to use as a warm-up or a light work out but those things can be very draining (for heavy duty stuff.) I used to spar with one on in the summertime and the sweat used to literally pour out when I stretched the elastic, but I don't like the dizzy feeling that usually accompanies it so I don't mess with 'em too much.
Summer's coming so be especially careful if you choose to use one.