In this Food Rules Live session I discuss the basics of fat and carbohydrate metabolism. While the science can get extremely complex, I want to simplify and review the basics. In the video, below, I discuss metabolic flexibility. That is, our bodies are capable of shifting between fat and carbohydrate utilization as a main energy source, depending on the state of our bodies. An understanding of basic human energy metabolism is important to provide context when discussing diet, fat loss, and performance.