Late-night eating linked to up to 30% higher liver disease risk in study of 200,000 people

PORTLAND, Ore. — That bowl of chips in front of the television at midnight may be doing more harm than expanding your waistline. A large new study suggests eating late at night could raise the risk of serious liver disease.

Researchers led by Oregon Health & Science University found that people who reported eating after dinner or after going to bed had a 20% to 30% higher risk of all forms of liver disease compared with those who did not. The findings were published Friday in the journal Clinical Gastroenterology and Hepatology.

The study focused on two conditions: metabolic dysfunction-associated steatotic liver disease, or MASLD, in which fat builds up in the liver, and cirrhosis, a scarring of the liver that can lead to liver failure.

"A few studies have hinted at this idea, but this is among the first long-term analyses to explicitly draw the connection to fatty liver disease," said lead author Dr. Robert Wilechansky, a hepatologist at OHSU who specializes in liver transplantation.

Data from nearly 200,000 people

The researchers analyzed three large, long-running U.S. datasets: the Nurses' Health Study, the Nurses' Health Study II and the Health Professionals Follow-up Study. Together, the studies included almost 200,000 participants who reported their diet and lifestyle habits over time.

The team grouped participants by their eating behaviors and then looked for links to reported cases of fatty liver disease or cirrhosis.

Late-night eating was defined broadly as eating after dinner or after bedtime. The researchers focused on the timing of meals and snacks rather than the type of food eaten.

According to one summary of the findings, people who ate late at night had a 36% higher risk of developing fatty liver disease and a 28% higher risk of cirrhosis.

Why timing may matter

The research adds to a growing body of evidence that the body's internal clock, known as the circadian rhythm, plays an important role in overall health.

Wilechansky said night shift workers, whose daily cycles are often thrown out of sync, have higher rates of obesity and heart disease. With up to 30% of the U.S. population affected by fatty liver disease, he wondered whether simple changes in meal timing could make a difference.

"We know the liver is very much in tune with the body's circadian rhythms," he said. "So we're interested in changing the timing of eating in a way that could make a difference in health, without changing the composition of what people eat."

Co-author Andrew McHill, an associate professor and sleep and circadian physiologist at OHSU, said the study builds on earlier research showing the importance of the body clock.

"We are seeing over and over again that the timing of behaviors, whether it's sleep, eating or exercise, really matters," McHill said.

He said previous work has shown that eating at night, when the body's internal clock is preparing for sleep, reduces the body's ability to process food efficiently. Over time, that can contribute to obesity, diabetes and, according to the new findings, poorer liver health.

McHill noted that animal studies have found the liver to be one of the organs most vulnerable to a mismatch between eating and sleeping times.

Late-night eating has also been tied to obesity and reduced insulin sensitivity, both key drivers of fatty liver disease.

A common and growing condition

Fatty liver disease, formerly known as non-alcoholic fatty liver disease, has become one of the most common liver conditions worldwide. It is closely associated with obesity, type 2 diabetes and high cholesterol, and often causes no symptoms in its early stages.

In some people, the condition can progress to inflammation, scarring and eventually cirrhosis. Symptoms of cirrhosis can include persistent fatigue and weakness, loss of appetite and itchy skin.

Wilechansky stressed that most people with fatty liver disease do not go on to develop its most serious forms.

"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," he said. "Even so, the big take-away here is that confining your calorie intake to several hours before bedtime might be beneficial."

Important limitations

The researchers cautioned that their study was observational, meaning it identified an association between late-night eating and liver disease but cannot prove that eating late causes it.

The findings also relied on broadly defined, self-reported data, which can be less precise than direct measurement. People who eat late at night may also share other habits or health characteristics that could influence their liver health.

Still, the authors said the results point to a clear direction for future research.

"Our findings add to the growing body of literature linking late-evening eating patterns to adverse metabolic and liver outcomes," the authors wrote.

New clinical trial underway

To test whether changing meal timing can directly improve liver health, Wilechansky is part of an OHSU team recruiting participants for a new study. That research will directly monitor eating behavior and examine whether eating earlier in the day improves clinical measures of fatty liver disease.

If the trial confirms the link, adjusting meal timing could become a simple, low-cost tool for protecting liver health, one that does not require people to change what they eat, only when they eat it.

What it means for consumers

While more research is needed, the study adds to evidence supporting time-restricted eating approaches, in which people limit meals to a set window during the day. Doctors generally recommend that people concerned about their liver health maintain a healthy weight, limit alcohol, stay physically active and talk with a health care provider about screening, especially if they have diabetes or obesity.

In addition to Wilechansky and McHill, the study's co-authors included Kevin Casey, Dr. Andrew Chan and Dr. Tracey Simon of Massachusetts General Hospital in Boston. The research was supported by the American Association for the Study of Liver Diseases Foundation.