i'm am not sure if this is true or not, but i heard that once your body reaches a high enough heart rate(say from high ********* running) your body starts to burn muscle instead of fat? Is this true? All i want to do is a cardio program to go along with my diet and weight training that will help me reduce my bodyfat. Also, is doing two different sessions of cardio( once in the morning and once at night) bad for you? Any suggestions or comments would be helpful