Everyone I know who has done P90X that I personally know has visually lost weight and that's all I hear from them besides how hard it is. I haven't done P90X but I do 5 3 1 and this is my 2 cents. I would do it if I was worried about body fat, muscle endurance, and cardiovascular endurance. You will not see any increase in actual muscle strength unless you are a noob lifter. It would put an unfit guy into fighting shape and that's how I see it.