Why would meal timing affect the liver?

One explanation involves circadian rhythms — the internal biological processes that regulate sleep, metabolism, and other functions across the roughly 24-hour daily cycle. The liver, which processes nutrients, regulates blood sugar, and manages energy storage, is particularly sensitive to these rhythms. Eating when the body is biologically preparing for sleep may interfere with those processes.

Wilechansky became interested in the question partly through evidence from night shift workers, whose schedules conflict with the natural sleep-wake cycle and who show elevated rates of obesity and heart disease. Animal experiments have likewise identified the liver as one of the organs most vulnerable to disruption of the normal relationship between eating and sleeping.

"We are seeing over and over again that the timing of behaviors, whether it's sleep, eating, or exercise, really matters," said co-author Andrew McHill, Ph.D., an associate professor specializing in sleep and circadian physiology at OHSU. "For example, we have shown that eating during the night, when the internal biological clock is promoting sleep, reduces the ability of your body to metabolize foods as efficiently and can eventually lead to obesity, diabetes, and now poor liver health."

Can eating earlier protect the liver?

The researchers urge caution. The study was observational: it identified associations between eating habits and health outcomes without directly testing whether shifting meal times prevents liver disease. It also relied on self-reported information, including fairly broad descriptions of when participants ate. Other factors could therefore explain part of the association.

The stakes also warrant perspective. "It's important to remember, of the people who developed fatty liver disease, only a small fraction develop serious forms of the condition like liver cirrhosis," Wilechansky said. "Even so, the big take-away here is that confining your calorie intake to several hours before bedtime might be beneficial."

A clinical trial now recruiting at OHSU aims to test the question directly. Rather than relying on recollections of past habits, the team plans to monitor meal timing and evaluate whether moving food consumption earlier produces measurable improvements in people with underlying fatty liver disease.

The appeal of the approach is practical: adjusting when meals are eaten may prove easier for some people than substantially changing what they eat. "Our findings add to the growing body of literature linking late-evening eating patterns to adverse metabolic and liver outcomes," the authors write.

The study team also included Kevin Casey, M.P.H., Andrew Chan, M.D., Ph.D., and Tracey Simon, M.D., of Massachusetts General Hospital in Boston. The research was supported by the American Association for the Study of Liver Diseases Foundation, award CTORA24-179910.

Perhaps better liver health begins not with a different plate, but with an earlier one.