If I lose 70 lbs, will my knee pain go away?

I have patellofemoral syndrome according to the doctor, which just means that I have pain behind the kneecap when I go up or down stairs or sit down or stand up. Also I have sore tendons above the kneecaps. I weigh 215 lbs and at 5" 6' I should weigh 145-150 lbs. I'm in a lot of pain whether I'm resting or walking, enough that Tylenol and ibuprofen have no effect at all. If I lose the weight, what change can I expect in the knee pain?