MetabolismCircadian Rhythm/ sur-KAY-dee-un RITH-um /The body's roughly 24-hour internal clock, which influences metabolism and the timing of meals. Related Terms Adipose TissueMETABOLISM Basal Metabolic Rate (BMR)METABOLISM Beta-Hydroxybutyrate (BHB)METABOLISM CatabolismMETABOLISM