Surprising lack of scientific answers here

Read any biochemistry text and its FACT that your bodies primary fuel when VO2 max is 50-60% is indeed FAT.
As that % increases, you switch to more carbohydrate fueled workout. You are still burning more fat as well but the % of fat to carb burned decreases, if that makes sense. That's why low intensity cardio post workout or upon waking is deemed a "pure" fat burning exercise.
High intensity will however create more EPOC effect. Meaning more fat will be burned hours after the workout, but it's not glycogen sparing like low intensity. So, yes there is a method to the madness that is not even debated in the human physiology world, it's fact. Cheers
