Physiological links between circadian rhythms, metabolism and nutrition

New Findings What is the topic of this review? This review provides a discussion of the links between circadian, metabolic and nutritional physiology, with a particular focus on mouse and human studies. What advances does it highlight? Links between circadian biology and metabolism exist from the molecular level through to whole‐organism physiology. Advances highlighted include the following: interactions between circadian clock genes/proteins and intracellular metabolic pathways; identification of the function of clocks in specific peripheral tissues; effects of timed feeding; and the variable effect of obesity on rhythms. Circadian rhythms, metabolism and nutrition are closely interlinked. A great deal of recent research has investigated not only how aspects of metabolic physiology are driven by circadian clocks, but also how these circadian clocks are themselves sensitive to metabolic change. At the cellular level, novel feedback loops have been identified that couple circadian ‘clock genes’ and their proteins to expression of nuclear receptors, regulation of redox state and other major pathways. Using targeted disruption of circadian clocks, mouse models are providing novel insight into the role of tissue‐specific clocks in glucose homeostasis and body weight regulation. The relationship between circadian rhythms and obesity appears complex, with variable alteration of rhythms in obese individuals. However, it is clear from animal studies that the timing and nutritional composition of meals can regulate circadian rhythms, particularly in peripheral tissues. Translation of these findings to human physiology now represents an important goal.