Yeah it's
possible to lose fat and improve performance because I've been there, but it's also tricky, not to mention a bit obsessive, to figure out just the right meal timing, food combinations and carb cycling. Even when you have it all planned out and working, progress in both simultaneously is still a headgame because it won't come as quickly as you'd like, and you could do it faster by focusing on one goal at a time.
If you dedicate 6-8 weeks solely to dropping the extra weight, you'd be done with it (depending how much you have to lose), won't have to worry about it anymore, get it outta your head and you can move on to focusing on performance improvements which will come pretty quickly once you can put all your attention on them.
Aerobics burns body fat but only for so long. First the body has to burn through its glycogen stores, then it Hits the wall and switches to fat burning but for just a short while. The body freaks out because biologically it is programmed to store fat for use in times of famine, not being forced into burning it any time the body owner decides to kick up their exercise. So at that point the body is under stress and it begins producing cortisol to deal with that stress, then the cortisol causes catabolization of muscle tissue for fuel.
Aerobics are still a neccessary part of a balanced training program, but 10 hours a week just might be a little overkill.
Anaerobic cardio exercise (high intensity short duration cardio) burns mostly just glycogen, actually spares muscle tissue and allows the body to turn to fat for fuel while it's at rest (ie: slow, long burn which doesn't throw the body into stress) leading to a leaner body over time and minimal muscle loss. Just compare the ultra-lean rock-hard physique of sprinters to the softer appearance of marathon runners and aerobic instructors.
Plus, the higher intensity training raises your lactate threshold which means when it's time for an endurance skate, you can push harder and faster than you could previously.
When all else fails, here's an article on overtraining:
http://en.wikipedia.org/wiki/Overtraining