I personally think if you want to burn fat and save muscle, DO SPRINTS!!!. I don’t care what body type you have, go to a football field and if you are in decent shape start at one end zone and sprint as fast as you can to the other end. You will be so dead after 2 or 3 if you have never done sprints.
When I say sprints I mean you are basically accelerating the entire time, your fastest point will be when you cross the endpoint. This is very difficult to really do because it is so grueling in my opinion. I played football in college and the most ripped of my teammates were always the running backs and they were always doing sprints.
Start with 100-yard sprints and if you have a decent diet you will see your legs get bigger and stronger and the fat will melt off.
Good luck