Hypothetical schematic overview of effects of fasting on small intestinal transporters and phase I/II metabolism genes. Not all results are summarized in this figure. The direction of transport is shown (↑) in the transporters, + means upregulated and – means downregulated during fasting. (A) Increased energy metabolism. (B) Diminished intestinal motility. (C) Elevated cholesterol secretion. (D) Increased xenobiotic metabolism. (E) Diminished capability of detoxification. (F) PPARα dependent regulated genes.