This word “metabolism” is thrown around a lot these days. You know that if yours is too slow you might gain weight. But what exactly does this all mean? Well technically “metabolism” is the word to describe all of the biochemical reactions in your body. It's how you take in nutrients and oxygen and use them to fuel everything you do. Your body has an incredible ability to grow, heal, and generally stay alive. And without this amazing biochemistry you would not be possible.