Delayed meal times reset body clocks

June 1, 2017, Cell Press
Credit: Vera Kratochvil/public domain

The human body runs according to a roughly 24-hour cycle, controlled by a "master" clock in the brain and peripheral clocks in other parts of the body that are synchronized according to external cues, including light. Now, researchers reporting in Current Biology on June 1 have found that at least one of those clocks can also be reset based on what time a person eats breakfast, lunch, and dinner.

The findings suggest that regular meal times might help people to keep their clocks on the same time, the researchers say.

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

Researchers knew that the body's clock system and metabolic control were tightly linked. Studies had also shown that circadian rhythms respond to meals. However, the researchers explain, it has only recently become possible to study relevant markers of the human body's many clocks, both inside and outside the brain.

In the new study, Johnston, along with Sophie Wehrens and their colleagues, enrolled ten healthy young men in a 13-day experiment in the lab. The men ate three meals at 5-hour intervals. All meals had the same calorie and macronutrient content.

Each participant started with a meal time set to 30 minutes after waking, and then, after getting used to eating early, they switched to a meal served 5 hours later for 6 days. After completing each meal schedule, the men underwent 37 hours of a specialized laboratory routine that allowed measurement of their internal circadian rhythms. The routine included dim lighting, small hourly snacks, limited physical activity, and no sleep.

The change in meal time didn't seem to influence hunger or sleepiness in the participants. It didn't change markers of the brain's master clock, including rhythms of melatonin and cortisol, or clock gene expression in the blood, either. However, the researchers discovered that later meal times significantly affected blood sugar levels. After late meals, blood sugar rhythms were delayed more than 5 hours on average.

"We anticipated seeing some delays in rhythms after the late meals, but the size of the change in blood sugar rhythms was surprising," Johnston says. "It was also surprising that other metabolic rhythms, including blood insulin and triglyceride, did not change."

The researchers also found that the rhythmic expression of a gene known as PER2, which encodes a core clock component, was delayed in fat tissue by about 1 hour. The findings show that molecular clocks in people may be regulated by meal times and that those shifts could underpin changes in blood sugar levels.

The findings suggest that people who struggle with circadian rhythm disorders, including shift workers and those on long-haul flights, might consider timed meals as part of an overall strategy to help resynchronize their body clocks. Now that the influence of meal times on human metabolic rhythms is clearer, the researchers say, it will be important to learn more about the health consequences.

Explore further: Cells in the retina light the way to treating jet lag

More information: Current Biology, Wehrens et al.: "Meal Timing Regulates the Human Circadian System" www.cell.com/current-biology/f … 0960-9822(17)30504-3 , DOI: 10.1016/j.cub.2017.04.059

Related Stories

Cells in the retina light the way to treating jet lag

April 18, 2017
Researchers have found a new group of cells in the retina that directly affect the biological clock by sending signals to a region of the brain which regulates our daily (circadian) rhythms. This new understanding of how ...

Gut microbe movements regulate host circadian rhythms

December 1, 2016
Even gut microbes have a routine. Like clockwork, they start their day in one part of the intestinal lining, move a few micrometers to the left, maybe the right, and then return to their original position. New research in ...

Disrupting the brain's internal clock causes depressive-like behavior in mice

November 29, 2016
Disruptions of daily rhythms of the body's master internal clock cause depression- and anxiety-like behaviors in mice, reports a new study in Biological Psychiatry. The findings provide insight into the role of the brain's ...

Disruption of the body's internal clock causes disruption of metabolic processes

December 7, 2016
Chronobiologists from Charité – Universitätsmedizin Berlin have shown that the body's carbon monoxide metabolism is closely linked to the body's circadian (internal) clock. Carbon monoxide, a toxic gas found in exhaust ...

Living against the clock: Does loss of daily rhythms cause obesity?

August 29, 2012
When Thomas Edison tested the first light bulb in 1879, he could never have imagined that his invention could one day contribute to a global obesity epidemic. Electric light allows us to work, rest and play at all hours of ...

Recommended for you

Synthetic sandalwood found to prolong human hair growth

September 19, 2018
A team of researchers led by Ralf Paus of the University of Manchester has found that applying sandalwood to the scalp can prolong human hair growth. In their paper published in the journal Nature Communications, the group ...

Separated entry and exit doors for calcium keep energy production smooth in the powerhouses of heart cells

September 18, 2018
Stress demands the heart to work harder and faster. To keep pace, the muscle must make its fuel at an accelerated rate. Bursts of calcium entering mitochondria—the cell's powerhouses—normally help control energy output, ...

First gut bacteria may have lasting effect on ability to fight chronic diseases

September 18, 2018
New research showing that the first bacteria introduced into the gut have a lasting impact may one day allow science to adjust microbiomes—the one-of-a-kind microbial communities that live in our gastrointestinal tracts—to ...

A new defender for your sense of smell

September 18, 2018
New research from the Monell Center increases understanding of a mysterious sensory cell located in the olfactory epithelium, the patch of nasal tissue that contains odor-detecting olfactory receptor cells. The findings suggest ...

Small molecule plays big role in weaker bones as we age

September 18, 2018
With age, expression of a small molecule that can silence others goes way up while a key signaling molecule that helps stem cells make healthy bone goes down, scientists report.

Sperm quality study updates advice for couples trying to conceive

September 17, 2018
Could doctors at fertility clinics be giving men bad advice? Dr. Da Li and Dr. XiuXia Wang, who are clinician-researchers at the Center for Reproductive Medicine of Shengjing Hospital in Shenyang in northeast China, think ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

gmurphy
not rated yet Jun 01, 2017
Fasting is a well-known trick for taming jet lag, it's called the Argonne diet protocol.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.