Stomach ‘clock’ tells us how much to eat
Nerves in the stomach act as a circadian clock, limiting food intake to specific times of the day, according to research from the University of Adelaide.
Researchers said the study, which was led by Dr Stephen Kentish and published on 5 December 2013 in the Journal of Neuroscience, could lead to new information about how the gut signals to the brain about when a person is full, and when to keep eating.
Stomach nerves respond to stretch
Researchers at the University’s Nerve-Gut Research Laboratory investigated how the nerves in the stomach respond to stretch, which occurs as a consequence of food intake, at three-hourly intervals across one day.
“These nerves are responsible for letting the brain know how much food we have eaten and when to stop eating,” said Dr Kentish. “What we’ve found is that the nerves in the gut are at their least sensitive at time periods associated with being awake. This means more food can be consumed before we feel full at times of high activity, when more energy is required,” he said.
“However, with a change in the day-night cycle to a period associated with sleeping, the nerves in the stomach become more sensitive to stretch, signalling fullness to the brain quicker and thus limiting food intake,” Dr Kentish said. “This variation repeats every 24 hours in a circadian manner, with the nerves acting as a clock to co-ordinated intake with energy requirements,” he said.
So far the research has been limited to laboratory studies and has not included humans.
“Our theory is that the same variations in nerve responses exist in human stomachs, with the gut nerves being less sensitive to fullness during the day and more sensitive at night,” Dr Kentish said.
Researchers said this could lead to further discoveries about how changes in people’s circadian clocks affect their eating habits.
“We know that shift workers, for example, are more prone to disruptions in sleep and eating behaviour, leading to obesity and other health problems,” said Amanda Page, study leader and Associate Professor at the University of Adelaide. “We are now conducting further research to see what kind of impact such changes to the circadian rhythm will have on eating behaviour, and how the nerves in the stomach react to those changes,” she said.
This study was funded by the National Health and Medical Research Council (NHMRC).