Re: too much running vs too much weights...whats worse???
So intense cardio like interval training burns muscle? If that's the case can you explain the physiques of sprinters?
Muscle size can vary day to day from simple things such as glycogen stores and water levels in the body. It isn't purely because you done some cardio a few times. Your lack of strength would be down to recovery or lack there of and nutrition. Again, not all down to doing some cardio.
BTW, your body uses muscle for fuel as a last resort. If you consume enough calories to fuel your workout (as Puma stated), catabolism does not become as issue.