Obesity, alcohol use and other factors are driving up rates of fatty liver disease among American adults, new research warns.

By 2018, federal data showed that 42% of adults had some form of fatty liver disease — higher than prior estimates, according to a team led by Dr. Juan Pablo Arab, a liver specialist with at Virginia Commonwealth University's Institute for Liver Disease and Metabolic Health, in Richmond.

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Hispanic adults were at especially high risk, the team noted, with nearly half (47%) affected.

The findings were published recently in the journal Nature Communications Medicine.

As Arab's team explained, fatty liver disease comes in many forms, but involves the slow buildup of fat deposits within the blood-cleansing organ.

There are three main kinds of fatty liver disease: metabolic dysfunction-associated steatotic liver disease (MASLD, caused by metabolic factors such as obesity and diabetes), alcohol-associated liver disease (ALD) and a combination of both syndromes, called MetALD.

According to the American Liver Foundation, advanced liver disease can cause jaundice, fluid retention, eye trouble and brain dysfunction. Over time, liver failure and fatal kidney complications can also occur.

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The new study was based on 2017-2018 data from the National Health and Nutrition Examination Survey, looking at the health of 5,523 adults.

MASLD is by far the most common form of liver disease, affecting 42% of adults. ALD and MetALD affect much lower percentages — 1.7% and 0.6% of adults, respectively.

Rates of fatty liver disease were more common in men than women, and rose with age.

The high rate of MASLD among Hispanics was surprising, given that one 2014 study found a much lower rate of Hispanics, 29%, had the disease at that time.

The Virginia researchers say genetics, as well as relatively high rates of obesity and diabetes, could explain why Hispanics are especially prone to MASLD.

For reasons that aren't clear, Black adults had the lowest rate of fatty liver disease.

What's driving the overall surge in MASLD among adults? According to the researchers, obesity and Type 2 diabetes are key factors.

About 65% of overweight adults have MASLD, the team said, rising to 90% among morbidly obese people.

At the same time, up to 70% of patients with Type 2 diabetes also have MASLD, Arab's group noted.

“This study highlights a significant health issue that affects a large portion of the U.S. population, and it shows that certain groups are at a higher risk,” Arab said in a university news release. “We hope these findings will guide more targeted health interventions to reduce the burden of liver disease, especially in high-risk communities.”