P90x is a gimmick product with really good marketing. There's nothing special about it. You workout 1hr/day, 6days/week and limit calories. Of course you will lose weight if you're eating like shit and lazy, going into it.

The biggest problem with it though is that it's a one size fits all program. How is that good for YOU? It's not. It's the same workout for everyone, male or female, fat or skinny and does not take anything into consideration. Individualization is the future pal, get on board and educate yourself. Don't buy the hype.