A new study from Keck Medicine of USC found that fast food consumption is associated with nonalcoholic fatty liver disease, a serious condition in which fat builds up in the liver. The study revealed that people with obesity or diabetes who consume 20% or more of their daily calories from fast food have severely elevated levels of fat in their liver compared to those who consume less or no fast food. The general population also has moderate increases of liver fat when one-fifth or more of their diet is fast food.