Your body follows a daily schedule. Sleep, hormones and many other processes rise and fall over about 24 hours.
New research suggests the liver may also be paying attention to another schedule: when food arrives.
In a study in mice, researchers found that regular feeding patterns helped organize daily changes in liver activity. When food was spread more evenly across the entire day and night, many of those normal patterns weakened or disappeared, even though the liver’s internal body clock was still working.
The findings were published in Science Advances.
The study helps explain why researchers are so interested in meal timing, but it does not show that people need to eat at certain hours, that late-night eating causes disease or that intermittent fasting is better for health.
The basic idea is that the liver appears to respond to more than one kind of timing signal.
Light helps set the body’s main internal clock. Food provides another cue.
When we eat, nutrients arrive and tell the liver that energy is available. That helps shape when certain jobs in the liver happen, such as processing and storing nutrients.
The researchers focused on a system called mTOR, which helps cells respond when nutrients are available. Rather than thinking of it as another body clock, it’s easier to think of it as part of the liver’s response to food.
In mice that ate during their normal active period, this system followed a clear daily pattern. When researchers blocked it, more than half of the liver genes that normally followed a daily rhythm lost that pattern. The liver’s main internal clock, however, continued to run.
That suggested meal-related signals were helping organize liver activity separately from the body’s built-in clock.
The researchers then tried the opposite experiment.
They gave mice small amounts of food throughout the entire 24-hour day, instead of allowing them to eat mainly during their usual active period. Under that schedule, many of the liver’s normal daily patterns faded.
Researchers were then able to restore many of those patterns by briefly changing mTOR activity at a regular time each day.
They saw a similar effect when looking at small molecules involved in metabolism. With a regular feeding schedule, 453 of these molecules followed a daily rhythm. That number dropped to 176 when food was spread across the day and night.
Taken together, the results suggest the liver is listening to at least two timing cues: the body’s internal clock and the timing of meals.
Lead researcher Jerome Menet of Texas A&M University described food as more than just a source of calories. “It also acts as a biological signal,” he said in the university’s news release.
That may eventually help explain what happens when eating schedules and the body’s internal clock are repeatedly out of sync, as can happen with shift work, jet lag or very irregular meal patterns.
But that part remains a question.
This study was done in young male mice, not people. Researchers looked at changes inside the liver, not whether the mice developed conditions such as diabetes, fatty liver disease, heart disease or cancer.
The study also did not test intermittent fasting in humans.
So while the findings may help scientists understand how meal timing could matter, they cannot tell us that dinner at 6 p.m. is better than dinner at 9 p.m. They also do not establish an ideal eating window.
What the study does show is simpler: when the mice ate changed the daily pattern of activity inside their livers.
That is useful because it adds another piece to the growing science of meal timing.
Eating does more than deliver calories and nutrients. It may also help tell the body when to prepare for the work of processing them.
The next step is figuring out whether the same system works the same way in people and whether changing meal timing actually leads to meaningful differences in health.
The research was supported by Texas A&M University and grants from the National Institute of Diabetes and Digestive and Kidney Diseases and the National Institute of General Medical Sciences, both part of the National Institutes of Health.