Does muscle break down fat? if I stop working out will I end up with a flat Butt again?

There's a saying " Muscle breaks down fat".I am 3 months PO and I was considering EMS " Electro Muscle Stimulation workout. If I work out my gluteus muscles will it break down the fat transfer? They put a suit on you, with electric patches on muscles . As you do a non impact 25 minute work out. It's suppose to help you develop stronger muscle faster results.