Just re-read this. That sauna suit isn't going to help you lose fat. Essentially all it's doing is dehydrating you by keeping your body temperature higher than normal when you work out. Your body tries to get rid of the excess heat by sweating. Then your body can get rid of the excess heat easier because heat is transferred easier through a liquid (the sweat).
You might burn some more calories, but the claims of double/triple the weight loss are marketing ploys to help them sell the product. The majority of weight will still be sweat which will be replenished when you drink at anytime after the workout.
Liken it to turning the thermostat at home up to 45 degrees all the time. You're gonna sweat a whole lot, but then you're gonna drink it all back in. No weightloss.
I know it's recommended for losing weight in the, VERY, shorterm. IE when fighters need to cut weight ASAP, the last few hours before a weighin or if they need to drop more weight in like an hour after they failed to make weight. Then they put as much water weight back on as possible before the fight. Anyone into physical fitness will tell you it's not a good idea to dehydrate for a long period of time, especially prior to exercise.
What it is good for however, is for your body getting used to exercising in extreme conditions. Also the more you submit your body to extended periods of sweating the less minerals (mostly salts) you will lose because of it.
Never use an instrument (I would say gimmick, but some of them do work. Though not to the extent they claim.) to try and replace actual work when concerning fitness. They can help, but not replace.