I strongly disagree with the original poster. I workout for 20 hours a week (15 cardio and 5 resistence training) mostly high intensity and I am in the best shape of my life after 5 years of ultra-low-carbing. I do 10 century rides each spring and fly by the carb-junkies. The body's main exercise fuel source is fat, that's why we store it so readily. The glucose-burning function (carb-burning) is an emergency "Fight or Flight" response to be used for rare, short bursts of energy. That's why we store so little glycogen in our liver and muscles, it's only our emergency reserve. Most Americans have become soooo out of shape that the only way they can do moderate exercise is by turning to these emergency reserves. Fat-burning is a much more effective and provides much more endurance. Take Stu Mittleman, the low-carb endurance athelete you did a marathon from San Diego to New York in just 56 days, while low-carbing!
JUST SAY NO TO CARBS! and get your body in better shape!