FEEDBACK NEEDED ASAP...... Just recd P 90X from a friend

Ok so I have been running about 2 miles 3 times a week and I have a couple of friends concerned that I am not getting any weight training in.  They Know that I have become a dont quit person since surgery.  So they pitched in together to get me the P90x program.  Obviously I will have to work at getting to up to form but I would like everyone's thoughts. 

i think my concern is that I will not be able to maintain the right number of calories in my system to sustain this type of program. 
Can anyone help?

Please keep in mind that my friends are concerned because they don't want me to lose any muscle tone.

My husband and I have P90X, its an intense program but there are modified versions of a lot of the exercises.  There are marathon runners on this board and they are able to get in the nutrition to fuel themselves during their races.  Speak with your nutritionist to make sure you're getting enough and that you don't have too much of a calorie deficit. Just do it at your own pace.  Building lean muscle also helps you burn fat too. Good luck

 
P90X is fantastic.

Your body gets fuel from your stored fat. So you've got plenty of fuel!

I trained for my first triathlon on 750-900 calories a day. As I got to the point where I was working out for 6-10 hours a week, I did up my protein and that did cause my calories to go up, but I was also 6 months out and almost to goal so I didn't have the fat stores that I did in the beginning.