At the liver, fructose is rapidly metabolized into glucose, lactose and glycogen. The body handles excess glucose consumption through several well-defined metabolic pathways, such as glycogen storage and de novo lipogenesis (creation of new fat). No such system is present for fructose. The more you eat, the more you metabolize. The bottom line is that excess fructose is changed into fat in the liver. High levels of fructose will cause fatty liver. Fatty liver is absolutely crucial to the development of insulin resistance in the liver.
