Insanity Nutrition?

AnimePrincess13

I am starting Insanity and was wondering the best way for factoring my calories to eat. i did the formula in the book they give you. However I have an HRM strap so it is pretty accurate for how many calories I burn. Would it be okay for me to just factor the calories I needed daily, subtract the 500 from it then add in my calories burned from my HRM and eat those back?

I don't want to mess it up, but I would like to use my new HRM if possible. Instead of just using the entire generic formula they have everyone use.

Thank you for any input.