The timing of food intake may be as significant for the general well being as what is being eaten, find researchers.
Experts at the Salk Institute for Biological Studies conducted experiments on mice and discovered that the daily waxing and waning of thousands of genes in the liver is mostly controlled by what is eaten and not by the body's circadian clock as was commonly believed.
Lead author Satchidananda (Satchin) Panda, Ph.D., an assistant professor in the Regulatory Biology Laboratory, said: "If feeding time determines the activity of a large number of genes completely independent of the circadian clock, when you eat and fast each day will have a huge impact on your metabolism."
Graduate student and first author Christopher Vollmers put normal and clock-deficient mice on strictly controlled feeding and fasting schedules while monitoring gene expression across the whole genome.
He said: "Food-induced transcription functions like a metabolic sand timer that runs for 24 hours and is continually reset by the feeding schedule while the central circadian clock is driven by self-sustaining rhythms that help us anticipate food, based on our usual eating schedule.
"But in the real world we don't eat at the same time every day and it makes perfect sense to increase the activity of metabolic genes when you need them the most.
Panda added: "Our study represents a seminal shift in how we think about circadian cycles. The circadian clock is no longer the sole driver of rhythms in gene function, instead the phase and amplitude of rhythmic gene function in the liver is determined by feeding and fasting periods-the more defined they are, the more robust the oscillations become."
Researchers who also contributed the work include postdoctoral researcher Luciano DiTacchio, Ph.D., graduate students Sandhyarani Pulivarthy and Shubhrox Gill, as well as research assistant Hiep Le, all in the Regulatory Biology Laboratory.
The findings were due to be published in the Proceedings of the National Academy of Sciences.