New research suggests that regular meal times could reset the master clock in the brain and other peripheral clocks in other parts of the body.
Jonathan Johnston of the University of Surrey says that, “a 5-hour delay in meal times, results in a 5-hour delay in body's internal blood sugar rhythms. We assume this is because of the changes in clocks in metabolic tissues of the body, but not due to the ‘master’ clock in the brain.”
Researchers understood that the body’s clock system and metabolic regulation are highly linked. Studies have also demonstrated that circadian rhythms act in response to meals. But the researchers clarify that it has only in recent times that it became possible to understand the related markers of the human body’s many clocks, both inside and outside the brain.
In the recent study, Johnston, along with Sophie Wehrens and their colleagues, included ten healthy young men in a 13-day experiment in the lab. The men consumed three meals at 5-hour intervals. All meals had similar calorie and macronutrient content.
The meal times were 30 minutes past walking, then eating early, and then 5 hours later for 6 days. When participants completed each meal in the schedule, they underwent 37 hours of a specific laboratory routine that permitted measurement of their internal circadian rhythms. The volunteers had small hourly snacks, dim lighting, limited physical activity, and no sleep.
Meal times and body clocks
Hunger and sleepiness were not affected by the changes in meal times for the participants. It did not modify markers of the master clock in the brain such as melatonin rhythms and cortisol or clock gene expression in the blood or both. But the researchers found that delayed meal times remarkably influenced blood sugar levels. After delayed meals, blood sugar rhythms were deferred more than 5 hours on average.
“We expected seeing some delays in rhythms after the delayed meals, but the amount of the change in blood sugar rhythms was shocking,” Johnston says. “It was also unexpected that other metabolic rhythms, such as triglyceride and blood insulin did not vary.”
The researchers also discovered that the rhythmic expression of a gene called as PER2, which encodes a core clock component, was deferred in fat tissue by about 1 hour. The results reveal that molecular clocks may be controlled by meal times and that those modifications could support changes in blood sugar levels.
The results propose that people who have circadian rhythm disorders, like shift workers and those on long-haul flights, could consider timed meals as part of a general approach to help resynchronize their body clocks. Now that the impact of meal times on human metabolic rhythms is understood, the researchers note, it will be significant to know more regarding the health consequences.