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Changing Meal Times Can Alter Your Body Clock

And there's more than one body clock.

DAVID NIELD
2 JUN 2017
 

Changing your meal times could be enough to reset one of your internal body clocks, researchers have found, giving us new insight into the relationship between when we eat and our body's circadian rhythms.

 

While previous studies have spotted a connection between nutrition, metabolism, and circadian rhythms in the human body, this new research pins down that relationship in more detail.

A team from the University of Surrey in the UK found that while a shift in meal times didn't affect the 'master' body clock – the one controlling when we get sleepy – it did cause changes in the cycle of blood sugar levels.

"A 5-hour delay in meal times causes a 5-hour delay in our internal blood sugar rhythms," explains one of the team, Jonathan Johnston. "We think this is due to changes in clocks in our metabolic tissues, but not the 'master' clock in the brain."

While we often talk about circadian rhythms as a group linked to a single body clock, we actually have multiple clocks spread throughout the body. These control our natural cycles and functions, which are all affected by factors such as light exposure.

The 'master' clock is located in a distinct set of cells in the hypothalamus part of the brain, but the researchers wanted to examine some of our minor body clocks as well.

 

Ten healthy volunteers were put on a specific meal schedule for six days, and then on a different meal schedule with a 5-hour delay for another six days.

After each six-day period, the participants were kept awake for 37 hours, with small snacks and dim lighting, in order to measure any change in their circadian rhythms.

Certain biological clock markers, such as sleepiness, and levels of melatonin and cortisol, didn't show any difference between the two schedules.

But in the blood sugar rhythms and the expression of a gene known as PER2 – an important internal clock component – there was a shift, and when our body clocks aren't synchronised, our bodies feel it.

"We anticipated seeing some delays in rhythms after the late meals, but the size of the change in blood sugar rhythms was surprising," says Johnston.

"It was also surprising that other metabolic rhythms, including blood insulin and triglyceride, did not change."

This is only a small study, and the results suggest eating patterns only affect some of our circadian rhythms, but the researchers think it could help those who need to resynchronise their body clocks after long-haul flights or late shift work.

 

Changing your breakfast time wouldn't necessarily cure jet lag completely, but it might help some of your body clocks get back on track.

Scientists have already seen signs of this delicate food and body clock balance in animals, indicating that our bodies really do respond best to some sort of routine.

And if you find yourself stuck in an irregular or damaging routines - all is not lost.

Research published earlier this year suggested that just one weekend of camping under the stars could be enough to reset circadian rhythms that have been bamboozled by our modern-day lifestyles, with late-night Netflix sessions and mid-afternoon naps.

"Our findings demonstrate that living in our modern environments contributes to late circadian timing, regardless of season, and that a weekend camping trip can reset our clock rapidly," explained one of the researchers, Kenneth Wright from the University of Colorado, Boulder.

And now this latest research shows food schedules could play a key part too.

"This report demonstrates that meal timing exerts a variable influence over human physiological rhythms, with notable changes occurring in aspects of glucose homeostasis," the Surrey team concludes.

The research has been published in Current Biology.

 

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