In new research, scientists at the University of Surrey tested the hypothesis that the human circadian system anticipates large meals.
Circadian rhythms/systems are physiological changes, including metabolic, that follow a 24-hour cycle and are usually synchronized to environmental signals, such as light and dark cycles.
Previous studies in this field have focused on animal controls and until now it has been undetermined whether human physiology can predict mealtimes and food availability.
“We often get hungry around the same time every day, but the extent to which our biology can anticipate mealtimes is unknown,” said University of Surrey’s Professor Jonathan Johnston, senior author of the study.
“It is possible that metabolic rhythms align to meal patterns and that regularity of meals will ensure that we eat at the time when our bodies are best adapted to deal with them.”
To learn more, 24 male participants undertook an eight-day laboratory study with strict sleep-wake schedules, exposure to light-dark cycles, and food intake.
For six days, 12 participants consumed small meals hourly throughout the waking period, with the remaining participants consuming two large daily meals (7.5 and 14.5 hours after waking).
After six days, all participants were then put on the same feeding schedule for 37 hours and received small meals hourly in a procedure known to reveal internal circadian rhythms.
Glucose was measured every 15 minutes during the study, and hunger levels were measured hourly during waking hours on days two four and six in the first stage of the study and then hourly for the final 37 hours.
The authors found the glucose concentration of participants in the small meal group increased upon waking and remained elevated throughout the day until declining after their last meal.
In the large meal group, there was a similar increase in glucose concentration upon waking however there was a gradual decline leading up to the first meal.
In the final 37…
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