But you are not always burning fat, that's the problem. If the body needs energy like right now and it doesn't have glycogen on hand and cortisol levels are elevated, then it will cannibalize muscle. This is the point I was trying to make earlier. Powerade is strictly for amateurs; serious cyclists (et al) are drinking Perpetuum or Spiz, both of which contain BCAAs and other proteins to offset gluconeogenesis.