Well-regulated eating habits are said to be important for health. A major breakthrough was the discovery of the negative regulatory feedback for transcription via the binding of Clock/Bmal1 to E-box, which forms the basis of biological clocks. Well-regulated eating habits normalize the liver clock gene, the rhythm of CYP7A1 gene, and blood cholesterol levels through insulin secretion. Moreover, well-regulated eating habits actively contribute to better lipid metabolism such as obesity, even if animals ingest a high-fat diet. From reported results so far, chrononutition has two important functions: 1) meal timing is important for our health, and 2) meal timing entrains our body clock.