Holding any pose for a length of time burns calories, but bikram adds the bonus of helping you lose excess water weight. The classes are held in rooms heated to 105 degrees and 40 percent humidity, which means you'll be drenched in sweat by the end of the 90-minute session. You'll go through 26 poses twice, holding each for a minute and a half the first time and 30 seconds the second time. If you have a big event coming up (can you say high school reunion?) and want to drop a few pounds fast, Imparato suggests practicing six days in a row, alternating between bikram and ashtanga for maximum fat-burning benefits.