Well, in my opinion it's the food only so far as she's getting more nutrients from it and therefore has more energy to burn. It's not a bad thing to have so much energy...it means she's healthy and sounds like normal puppy behaviour to me! My 5 month old pup just in the last week started doing what yours is doing...tearing around the place, digging frantically, and basically acting like a nutter.
I think he's just being a puppy.
