I didn't follow the P90X diet plan specifically. However, I had been on a diet that had a fixed daily caloric intake with specific goals with regards to fat, carbs and protein intake. Basically I stuck a 2400 calorie/day diet where the fat/carb/protein percentages were 15/50/35 respectively. My goal for P90X was to simply stick with it for 90 days, which I did. I had already been losing weight prior to starting the program, so my weight loss while on the program was only about 12lbs. However, the addition of lean muscle has helped me lose an additional 8-10lbs since ending the program. My goal is hit 200lbs and I'm 18lbs away, so it's getting close! :)
How is your program treating you??