There is no doubt that every person that is often going to the gym will tell you that to achieve the desired result it is necessary to do some cardio exercises. However, in reality it works other way. In that case you will burn muscles but not the fat. First of all, you have to understand that cardio exercises really help to burn stored fat. Still, in reality the body will replace that fat for the next workout. In that case you just have to be aware of the fact that cardio exercises are not aimed at burning fat. If the fat reserve is not available then there is no doubt that your body will will use lean muscle. At the same time you can move to the starvation mode, but it will not help too, because in that situation the body will hold fat instead of burning it.