Hey,

i do a lot of MMA training like jiu jitsu, wrestling, boxing etc etc so basicly i just do a lot of cardio. Im lifting 5 times a week as well pretty hard and im getting pretty big but i feel like what ever muscle gains i make in the gym always jus melts away after all the cardio i do.
What is the trick to maintaining muscle mass while doing so much cardio, i eat good and have 2 protein shakes a day as well.