Bikram yoga made me lose weight, too much weight, in fact. I became very hot and too dry, and not just during class. No matter how much water I drank before, during, and after class, I would still wake up at 2:00AM sweating hot with a terrible thirst. Although it did help with rectifying knee pain I've had (likely from the weight loss), I think doing it every day as the teachers recommended was a bit depleting for my constitution.
I'm a little too overheated, lean, and limber to begin with--a real
vata/pitta type, ayurvedically. I do better with slower, cooler exercise like hatha yoga and tai chi chuan. I think those who tend to being cold, stiff-jointed, tight-muscled, and who put on weight easily really take to Bikram's yoga very well. It really revs up your metabolism and gives you a burst of energy.
My advice to anyone, though, is to not pay attention to what others' bodies are doing in the big mirror; don't try to push yourself competitively to go as deep into poses as the person next to you. "Yoga" and "competition" goes together about as much as "poetry" and "competition": somewhere, somehow, someone's going to get hurt, and it isn't gonna be pretty.
Don't mess with
Bikram Choudhary, BTW. Upon patenting his yoga sequence, he was quoted as saying, "I have balls like atom bombs, two of them, 100 megatons each. Nobody f*cks with me." Which, if I were looking for a guru, would be just the exact mantra I'd want to get. Righteous!