The beneficial effects of intermittent fasting: an update on mechanism, and the role of circadian rhythm and gut microbiota.

IMPORTANCE: There is accumulating evidence that intermittent fasting (IF) is connected to improved health condition and longevity time-restricted feeding (TRF) is the most recognized and extensively studied model of IF. OBJECTIVE: To investigate the underlying mechanism of pleiotropic benefits of IF and hint the most advantageous feeding pattern for humans. EVIDENCE REVIEW: We searched MEDLINE, EMBASE, Cochrane Library and Google Scholar by 2020 April for publications on IF or TRF and their mechanisms. Studies include animal models and human cohorts. FINDINGS: One important mechanism is that IF allows certain period of fasting time, in which our bodies activate pathways of repair and rejuvenation. Moreover, the advantages of IF, especially TRF over total caloric restriction (CR) provided bases for various animal and human studies which suggested that the feeding-fasting rhythm stimulates the fluctuation of our gut microbiota and a series of subsequent molecular alterations, which in turn restored a healthier circadian clock that resembled our inherent clock formed throughout millions of years of homo sapiens history. CONCLUSIONS AND RELEVANCE FOR REVIEWS: Complete understanding of the mechanism leading to the beneficial effects of IF paves the way for tailored dietary regimen to combat a wide range of diseases and ill health conditions.