" When you do your cardio workout, you are burning calories. Lets say you wake up, eat breakfast, eat lunch later in the day, and then a few hours after lunch, you do your cardio. All you will be doing during that cardio is burning the calories and carbs of the food you just ate. When you do cardio first thing in the morning, you haven't eaten anything for the last 8 or so hours because you were sleeping. So, when your body sees that there are no carbs to burn, it goes directly to stored bodyfat. And stored bodyfat is the fat that is on your body, which is the fat that you want to lose! "