Effect of feeding regimens on circadian rhythms: Implications for aging and longevity

Increased longevity and improved health can be achieved in mammals by two feeding regimens, caloricrestriction (CR), which limits the amount of daily calorie intake, and intermittent fasting (IF), which allows the food to beavailable ad libitum every other day. The precise mechanisms mediating these beneficial effects are still unresolved.Resetting the circadian clock is another intervention that can lead to increased life span and well being, while clockdisruption is associated with aging and morbidity. Currently, a large body of evidence links circadian rhythms withmetabolism and feeding regimens. In particular, CR, and possibly also IF, can entrain the master clock located in thesuprachiasmatic nuclei (SCN) of the brain hypothalamus. These findings raise the hypothesis that the beneficial effectsexerted by these feeding regimens could be mediated, at least in part, through resetting of the circadian clock, thus leadingto synchrony in metabolism and physiology. This hypothesis is reinforced by a transgenic mouse model showingspontaneously reduced eating alongside robust circadian rhythms and increased life span. This review will summarizerecent findings concerning the relationships between feeding regimens, circadian rhythms, and metabolism withimplications for ageing attenuation and life span extension.