Contrary to what is usually said, the sauna does not contributes to loosing weight! The loss of weight is to bring back to the expulsion of liquids (from 500 g. to 1500 g.), that are immediately regained as soon as you drink.
Nevertheless there are positive implications as regards loss of weight. Actually is the sauna a good exercise concerning stimulation for blood and kidney circulation, what gets metabolism going again and helps to burn excessive fats.