The more muscle you have the more calories you burn without doing nothing. I can tell you i sweet alot during each meal ( this is a sign of quick metabolism?)
In the past doing fasted cardio slow bike for 60 minutos i lost 4 pounds . i always lose weight during my workout even using intra workout carbs.
Bodybuilders over 225lb needs cardio off season? and to burn fat pre contest ? remenber we use fat burners like clenbuterol , yohimbine, t3 and hgh . why do cardio?
Nathan the Asha said dont do any cardio ever and alot of pros dont do it. Heavy bodybuilders can lose alot of muscle doing cardio.

What about cardiovascular health?
Eating alot and getting over your genetic limit with different drugs will add some weight on your heart, low cardio will help some blood flow to different organs and muscles , and reduce insulin resistance.
Sweating and losing water is not a sign of losing muscle, weight is relative.