When doing cardio for more than 20 minutes, the body begins to catabolize the protein from your muscles. That's something you don't want to happen if your ultimate goal is weight loss. 1 pound of muscle will have your body burning an extra 50 calories per day JUST to maintain that muscle.
I've got 2 new books I'm reading right now. Once I'm through reading, I will put them into practice. First one is called Powerfoods and the other one is called the Abs Diet. Both are from Rodale Books and Men's Health. If you get a chance, see if your local library has a copy you can check out. If not, they're around $30 each. WELL worth the investment for what I want to do to my body.