It is a common misconception that your metabolism is an organ or single piece of your body, something you can replace, fix or clean. Your metabolism is actually the sum of all your processes in your body; it is everything that goes on as a whole. When something is talking about speeding up or slowing down your metabolism he or she can actually be referring to just about anything in you. The way a car uses fuel is a great example.  How fast a car goes is dependent on its part and how well the car uses its fuel.  How well it uses its fuel would be its metabolism so to speak.  So to increase the cars performance there are countless things that can be modified, upgraded, switched out or cleaned to make it run better or faster.  Your body is just the same (so to speak), by cleaning and strengthening any and all components of your body, you power up your metabolism.