http://fitsugar.com/821509
One of my friends actually recommended doing cardio on an empty stomach, first thing in the morning. With exactly the same rationale behind it as stated in this article. I did it, a couple of times. I used to do pilates every morning before breakfast, too.
Now, though, I usually have dinner 4-6 hours before I end up going to bed. By the time I wake up, I'm starving! So when I workout in the mornings, which really is the way to go, I usually do it ~3 hours after a good breakfast.
"After fasting all night, since you don't eat while you sleep, your glycogen (or carb) stores are low. Glycogen is the fuel the body generally burns first for energy. If your glycogen levels are low and your body is in motion, your body decides to hold on to your fat. The body is essentially paranoid and thinks a famine might be coming, so it holds on to the fat as emergency reserve and targets muscle instead."
I'm skeptical about the idea that the body can "think a famine is coming" within a ~ 1 hour workout session. Probably if you do a hardcore tri or marathon on an empty stomach, this rationale would make sense. Otherwise, I'm not convinced.
