First off Muscle is Muscle. Lean or big and bulky. Your resting metabolic rate (RMR) (the calories you burn while at rest) will generally be higher in people that have more muscle.
If you are on a diet and losing weight you will lose muscle and fat. Thats just thee way it goes….So consuming more protein in your diet during a cut will help offset the muscle loss during a restrictive diet.
Protein also is also slower to digest which means you will feel fuller for longer and burn more calories during digestion! Digestion burns up a lot of the calories that your using in your RMR.