A high-fat diet can disrupt the body's internal clock and cause behavioural changes, according to a new study.
Researchers at Northwestern University discovered that mice fed on a high-fat diet deviated from their normal activity patterns - for instance eating during the day when they were supposed to be sleeping.
The findings of the team have been published in the November issue of the journal Cell Metabolism.
"We found that, as an animal on a high-fat diet gains weight, it eats at the inappropriate time for its sleep/wake cycle. All of the excess calories are consumed when the animal should be resting," said Joe Bass of Northwestern University who led the research team.
"You can begin to see changes in the animals' daily habits very rapidly within a matter of days," he added.
In recent years, scientists have been paying increasing attention to the connection between the circadian network and metabolism.
For instance, Bass's group and others recently uncovered a link between the body clock and metabolism. While the effects of the molecular circadian clock on metabolic processes are well documented, Bass said, much less is known about how metabolic processes may alter the circadian clock.
In the new study, the mice received 45 percent of their calories from fat. For humans, it's recommended that no more than 30 percent of calories come from fat.
"It's not only activity and feeding that shifts, but also the molecular processes involved in metabolism," Bass said.
"The changes appear to be global. The clock is an ancient mechanism for matching behaviour to changes in the external environment that vary in accordance with the rotation of the earth, and the cycle of light and darkness. We now show that the clock is also clearly influenced by the composition of the diet."