If you do too much acting in a lead part in a feature film where you're 40 ft. high, it's rather unattractive. You can see the acting. And it's actually the right thing to do to bring as much of yourself, I believe, to the part as you possibly can - to minimize the amount of theatrical stuff that you need to do.
I eat as much as the next girl but I work my butt of in the gym every morning! The key is moderation. I splurge on the weekend. A big bowl of pasta and a delicious slice of cake for dessert are my favorites.