Will P90X help me lose weight and get in better shape?

Im 5'5, female, and i weigh 128lbs. By summer, i want to weigh about 115 but also have some muscle. Im going to start P90X Lean on Monday(that's when it gets delivered) and i was wanting to know how long it will be for me to see results? And I'm a vegetarian so I also wanted to know if I follow the nutrition plan except for when it says to eat meat, I was just going to eat a boca burger(its only 70 calories). So do you think I would lose a lot of weight and gain muscle?