Scheduled meals and scheduled palatable snacks synchronize circadian rhythms: Consequences for ingestive behavior

Food is a potent time signal for the circadian system and has shown to entrain and override temporal signals transmitted by the biological clock, the suprachiasmatic nucleus, which adjusts mainly to the daily light/dark (LD) alternation. Organisms mostly ingest food in their active period and this permits a correct coordination between the LD and the food elicited time signals with the circadian system. Under conditions when feeding opportunities are shifted to the usual resting/sleep phase, the potent entraining force of food, shifts circadian fluctuations in several tissues, organs, and brain structures toward meal time, resulting a desynchrony within the body and between the organism and the external LD cycle. The daily scheduled access to a palatable snack exerts similar changes specifically to brain areas involved in motivation and reward responses. This review describes the phenomenology of food entrainment and entrainment by a palatable snack. It suggests how scheduled feeding can lead to food addiction and how shifted feeding schedules toward the sleep phase can result in altered ingestive behavior, obesity and disturbed metabolic responses.

Research highlights
► In this manuscript we describe the relevance of circadian rhythms for feeding behavior.
► We explain the relevance of fixed feeding schedules on temporal patterns of metabolism.
► We describe the driving force of feeding on brain activity and daily clock gene oscillations.
► We describe the relevant and selective influence of daily snacks on corticolimbic structures.
► We discuss the influence of daily feeding schedules on development of addictive behaviors and obesity.