We know that a surplus in calories causes both fat and muscle gain.
We also know that the body has two fuel sources, fat and carbohydrates.
It is known that cardio at a low intensity uses a high percent of fat as it's fuel source. Most of the calories that are burn are from fat.
So the key to quickly and effectively build muscle while losing excess fat is to eat around 10% more calories than we burn (including those burned during cardio), and run at a long, low-intensity pace to get rid of the built up fat.
Anyone like to rebut?
Thread: How to gain muscle and lose fat