Originally Answered: P90x diet plan.?!?!?
It's much more complicated then calculating how much you can eat because it goes by phases. Phase one is fat shredding, two is energy boosting and three is endurance maximizer. I'll give you the basic formula.
First calculate your RMR (resting metobolic rate) - this is basically what you need to survive.
Body weight x 10 = RMR in calories
Then calculate your DAB (Daily Activity Burn) - this is what you need to do your regular daily activities. Take into account this number is skewed if you play x-box all day vs work in construction.
RMR x 20% = DAB
Finally, add your calories needed to get you through your workouts (average P90x workout will burn 600 calories)
RMR + DAB + 600 = Energy amount
Now, use that number to know your nutrition level. If your total outcome is 1,800-2,399 you need to consume 1,800 calories per day and are in level 1. If your total outcome is 2,400-2,999 you need to consume 2,400 calories per day and are in level 2. I fyour total outcome is 3,000+ you need to consume 3,000 calories per day and are in level 3.
Once you have all that figured out, you need the nutritional manual to actually show you the diet plans. It's far too involved to type here but perhaps you can find a download online, or have your inlaws call Beach Body and send them a replacement Nutrition Plan Booklet.