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There may be something to the widely debunked jet lag diet, after all.
British researchers found evidence that when you eat can affect your body clock. When they moved meal times forward by five hours in volunteers, they found changes in circadian rhythms — the human body clock.
"A five-hour delay in meal times causes a five-hour delay in our internal blood sugar rhythms," said Jonathan Johnston of the University of Surrey, who led the study.
"We think this is due to changes in clocks in our metabolic tissues, but not the 'master' clock in the brain."
The findings might help people fight jet lag and might lead to ways to help shift workers, Johnston said.
“Your mealtime has a big effect on things such as your glucose control,” Johnston told NBC News.
“Maybe we can come up with strategies to help people overcome some of the problems of shift work. At the moment, people will use things like the timing of light exposure and supplements such as melatonin,” Johnston added.
“What we predict is it will be a similar timing for your meals as well.”
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Johnston and colleagues set up an intense experiment using 10 volunteers. They asked to them precisely time their meals for a few days, and then brought them into the lab for careful control, changing the timing of meals and their exposure to light.
“They lived in the lab for nearly two weeks,” Johnston said. At first the volunteers, all young men, kept a regular, normal schedule with meals at somewhat conventional times.
Then they kept the volunteers awake with the lights on for 37 hours straight, feeding them light snacks every hour. Finally, they delayed meals for five hours, while keeping sleep and light schedules at normal hours for six days straight.
Johnston’s team tested the men’s blood and tissue regularly during the experiments to see what changing meal times would do.
What they found were changes in blood glucose levels, but not blood lipids or insulin, they reported in the journal Current Biology. They also found changes in the activity of a gene called PER2, which is involved in circadian rhythms and sleep disorders.
"We anticipated seeing some delays in rhythms after the late meals, but the size of the change in blood sugar rhythms was surprising," Johnston said. "It was also surprising that other metabolic rhythms, including blood insulin and triglyceride, did not change."
It was a small study and involved just 10 young men, but it fits in with other studies on meal timing. The American Heart Association has advice on timing meals, for instance.
“We know that shift workers are more likely to have obesity, diabetes and cardiovascular disease,” Johnston said. “Part of the reason is their clocks aren’t properly synchronized."
So next time the flight attendant wakes you up to serve breakfast on that overnight flight, it might be best to sit up, shut up and eat it.