A comparison of a healthy liver (top) and an unhealthy, fatty liver (bottom). The liver is a large organ, about the size of a football, located in the upper right abdomen underneath the ribs. It plays a major part in many core bodily functions such as metabolism, digestion, and detoxification. However, consuming excess calories, especially in the form of refined sugars, can cause fat to be stored in the liver--leading to a condition known as nonalcoholic fatty liver (NAFLD). The excess fat can lead to inflammation of the liver, which can become scarred and hardened.