I've always been against any sort of working out before eating. Your body is rpactically starving after being asleep for 8+ hours. You'll end up buring more muscle than you will fat by working out first thing in the morning on an empty stomach.
It might help some people, but it's not any better than doing it after you eat.
http://www.bodybuilding.com/fun/the-myth-of-cardio-before-breakfast-debunked.html