New research suggests otherwise, according to a Keck Medicine of USC study published today in Clinical Gastroenterology and Hepatology. 

Researchers discovered that people with metabolic dysfunction–associated steatotic liver disease (MASLD), the most common liver condition in the country affecting one-in-three adults, face significantly higher risk of liver fibrosis, or harmful scarring of the liver, if they engage in episodic heavy drinking. Episodic heavy drinking is four or more drinks in one day for women and five or more drinks in one day for men, at least once a month.  

Those who consume large amounts of alcohol in a single day at least once per month are three times more likely to develop advanced liver fibrosis than individuals who spread out the same total alcohol intake over time, according to the findings. 

Younger adults and men were more likely to report episodic heavy drinking, and the more drinks consumed at one time, the more liver fibrosis people tended to have. 

“This study is a huge wake-up call because traditionally, physicians have tended to look at the total amount of alcohol consumed, not how it is consumed, when determining the risk to the liver,” said Brian P. Lee, MD, MAS, a hepatologist and liver transplant specialist with Keck Medicine and principal investigator of the study. “Our research suggests that the public needs to be much more aware of the danger of occasional heavy drinking and should avoid it even if they drink moderately the rest of the time.”  

How the study was conducted 

Lee and his colleagues used data from the nationally representative National Health and Nutrition Examination Survey, a long-running health survey of the United States population. They included data from more than 8,000 adults, collected between 2017 and 2023. In particular, they looked at the link between episodic heavy drinking and advanced liver fibrosis to understand how drinking patterns — not just total drinks — may cause harm even to moderate drinkers, which is considered seven drinks a week for women and 14 or less for men.  

The research team focused on MASLD because of its prevalence among Americans. MASLD affects people with excess weight, obesity or other metabolic conditions, such as Type 2 diabetes, high blood pressure or high cholesterol, and is on the rise. Additionally, while MASLD is not defined as alcohol-related, Lee and his colleagues wanted to explore if alcohol did in fact play some role in the condition. 

More than one-half of the adults included in the study reported episodic heavy drinking and almost 16% of patients with MASLD were episodic heavy drinkers. 

The researchers compared people with MASLD with the same age, sex and average weekly alcohol consumption, segmenting some as episodic heavy drinkers and others as non-episodic heavy drinkers, to reach their conclusion that episodic heavy drinkers with MASLD had nearly three times higher odds of experiencing advanced liver fibrosis.  

Lee speculates that episodic heavy drinking can harm the liver both directly and indirectly. Drinking large amounts of alcohol at once can overwhelm the liver and increase inflammation, which leads to scarring and damage. People with MASLD may be particularly at risk, as Lee’s previous research has shown that obesity, high blood pressure and other conditions associated with MASLD can more than double liver disease risk. 

Alcohol-related liver disease has more than doubled in the last two decades, according to Lee. He believes this trend is driven by pandemic-era surges in drinking and an increase in people with risk factors for MASLD, like obesity and diabetes.  

“Although this study focused on patients with MASLD, these findings may also be pertinent to a broader patient population,” said Lee. “With more than half of adults reporting some episodic heavy drinking, this issue deserves further attention from both physicians and researchers to help better understand, prevent and treat liver disease.” 

What explains the different outcomes?  

The answer may lie in a condition known as metabolic syndrome, a cluster of conditions that together raise the risk of coronary heart disease, diabetes, stroke and other serious health problems. This syndrome, characterized by symptoms such as abdominal fat, high blood pressure, high cholesterol and high blood sugar, affects more than one in three Americans.  

A new study from Keck Medicine of USC published in the Annals of Internal Medicine shows that heavy alcohol use may be dramatically more damaging to the liver for people with metabolic syndrome.  

“Our research suggests that metabolic syndrome and alcohol interact in such a way that they multiply the effect of alcohol on the liver, more than doubling the risk of advanced liver disease among heavy drinkers,” said Brian P. Lee, MD, MAS, a hepatologist and liver transplant specialist with Keck Medicine who is the lead author on the study. “Drinking is harmful to the liver, but especially so for this segment of the population.”  

In the study, heavy alcohol use was defined as two drinks (a total of 12 fluid ounces) a day for women and three drinks (a total of 18 fluid ounces) per day for men.  

Lee and his colleagues were motivated to research a connection between advanced liver disease, alcohol use and metabolic syndrome after noticing that between 2009-2018, deaths from alcohol-associated liver disease surged in the United States by more than 30% while alcohol use, including heavy drinking, remained stable or declined.  

During the last 20 years, the number of Americans with metabolic syndrome increased significantly. Previous research has shown that metabolic syndrome can cause liver abnormalities.  

“We therefore hypothesized that metabolic syndrome could be an important contributor to this unexplained surge in advanced liver disease,” said Lee.  

For the study, Lee and his fellow researchers used data from the National Health and Nutrition Examination Survey, which assesses the health and nutritional status of adults and children in the United States, pulling together samples representing the U.S. population 20 years or older between 1999 and 2018. 

While the data revealed a slight increase in advanced liver disease with heavy alcohol use without metabolic syndrome, the greatest increase in advanced liver disease was found in those with combined heavy alcohol use and metabolic syndrome. 

Lee believes that the increased risk of liver damage from drinking is a result of an increase in the amount of fat in the liver. A healthy liver contains less than five percent fat; any more than that can lead to inflammation and cirrhosis (scarring) of the liver, liver cancer and liver failure.  

“Both metabolic syndrome and drinking increase liver fat, and we think that the combination of the two accelerates the accumulation of fat in the liver and fuels inflammation, resulting in a greater chance of liver disease,” said Lee.  

He hopes the study will encourage physicians who screen and diagnose patients with metabolic syndrome to also ask about alcohol use and look for liver disease.  

“Our study indicates that these conditions may often coexist, and it is in patients’ best interest to address both issues,” he said. “It’s also important for people with metabolic syndrome to realize they may be at an increased likelihood of advanced liver disease, and to monitor their drinking accordingly,” he added.  

The other authors of the study are Jennifer Dodge, MPH, assistant professor of research medicine and population and public health sciences with the Keck School of Medicine of USC;  Wendy Mack, PhD, professor of population and public health sciences with the Keck School of Medicine; Adam Leventhal, PhD, professor of population and public health sciences with the Keck School of Medicine and director of the USC Institute for Addiction Science and Norah Terrault, MD, MPH, a Keck Medicine gastroenterologist and division chief of gastroenterology and liver diseases with the Keck School of Medicine.