Metabolism can be defined as the chemical processes that occur within a living organism in order to maintain life. The two types of metabolic reactions are catabolic and anabolic. I think it’s the Thyroid that regulates metabolism. Lastly, metabolism is the process of converting food to energy therefore it effects energy.
Okay, this is an interesting one but mainly no, most activity's will so you don't push yourself but if you really wanted to you could go for however long you want as long as you are not doing harm to your body, depending if you are on a fitness program there will be limits.
Nutrients are compounds in foods essential to life and health, providing us with energy, the building blocks for repair and growth and substances necessary to regulate chemical processes.
