Molecular mechanisms underlying the association between circadian clock and metabolic pathways. CLOCK/BMAL1 heterodimer activates transcription of genes directly related to metabolism, especially nuclear receptors Reverbα and Rorα (members of clock machinery) and Ppar family of transcriptional factors (clock-controlled genes; do not participate of clock machinery itself). RORα and PPARα activate Bmal1 and Reverbα expressions. REVERBα represses Bmal1, Rorα and its own transcription. PPAR family and BMAL1 are involved in glucose and lipid metabolism and adipogenesis. REVERBα and RORα are implicated in the regulation of glucose, lipid and lipoprotein metabolism, adipogenesis and lipogenesis. They can also cross-talk with other important genes of metabolism such as PGC-1α (PPARγ- coactivator- 1α). Straight lines: stimulation. Dashed lines: inhibition.