Fatty Liver Is More Common Than You Think, and Most People With It Don't Know

Fatty liver used to sound like a heavy drinker's problem. The numbers say otherwise. In a national sample of US adults who had their livers scanned, 42.1 percent had a fatty liver, and 89.4 percent of those cases were the metabolic kind, now called MASLD. That works out to roughly 38 percent of US adults, close to 4 in 10.

The new name, MASLD, says what drives it

In 2023, three large international liver associations replaced NAFLD (nonalcoholic fatty liver disease) with MASLD: metabolic dysfunction-associated steatotic liver disease. The decision came from 236 panelists, experts and patient advocates from 56 countries. Under the new definition, a diagnosis needs fat in the liver plus "at least 1 of 5 cardiometabolic risk factors."

Part of the reason was the old words themselves. "Nonalcoholic" and "fatty" were felt to be stigmatizing by 61 percent and 66 percent of the panelists. The new name puts the focus on metabolism, which is where the research points.

The panel also created a middle category, MetALD, for people with metabolic risk factors who also drink more. For women the range is 140 to 350 grams of alcohol a week. At about 14 grams of alcohol in a standard drink, that's roughly 10 to 25 drinks a week. So the line between "alcohol" fatty liver and "metabolic" fatty liver is less clear than the old names suggested.

Worldwide, it climbed from about 1 in 4 to almost 4 in 10

A review of 92 studies put the global rate at about 30 percent of adults. More striking is the trend: the rate rose from 25.26 percent in 1990 to 2006 to 38.00 percent in 2016 to 2019, an increase of about 50 percent.

Younger adults aren't exempt. Among Americans aged 15 to 39 who don't drink heavily, 40 percent showed signs of fatty liver on a FibroScan, a type of ultrasound that measures liver fat.

Thin people get it too

Fatty liver isn't only a weight issue. In a meta-analysis of people with fatty liver around the world, 19.2 percent were lean and 40.8 percent were not obese. The authors' conclusion: "obesity should not be the sole criterion" for screening.

Extra sugar gets stored as fat, and the liver is one place it goes

Dr. Jarod Ward points to what happens with sugar the body can't use right away:

"Your body takes too much sugar and converts it into fat, because sugar burns quick, fat burns slow. So if you keep eating those quick burning calories, your body's like, I have too much quick, let's put some in reserve."

The research on sugary drinks fits that picture. In the Framingham Heart Study, people who drank one or more sugar-sweetened drinks a day had 61 percent higher odds of fatty liver than people who drank none. More in Sugar and Your Liver.

Why more than 95 percent of people with it don't know

The NIH describes MASLD as "a silent disease with few or no symptoms." When it does show up, "you may feel tired or have discomfort in the upper right side of your abdomen." That tiredness is real: in one study, people with fatty liver scored 51 on a fatigue scale, against 8 in people without it.

Because it's quiet, awareness stays low. In US survey data from 2001 to 2016, "more than 95%" of people with signs of fatty liver did not know they had liver disease.

Routine blood work can miss it too. A gastroenterology guideline puts a truly healthy ALT, a common liver enzyme, at 19 to 25 IU/L for women, while the older lab cutoff for women was 30. And a biopsy study found "the entire histologic spectrum" of fatty liver disease in people whose ALT was normal. A full picture takes more than one number, which is why Dr. Jarod runs lab testing as part of his functional medicine work.

What research shows helps

The same habits come up again and again:

• Weight, when there's weight to lose. In a year-long study of people with fatty liver inflammation, losing 10 percent or more of body weight resolved the inflammation in 90 percent of them.
• A Mediterranean-style diet. In a six-week trial, it cut liver fat 39 percent, against 7 percent on a low-fat diet, "even without weight loss."
• Less added sugar. When children swapped added sugar for starch at the same calories, liver fat fell from 7.2 percent to 3.8 percent in nine days.
• Movement. A review of 12 controlled trials found exercise lowered liver fat "with minimal or no weight loss."

How to keep those habits going after three weeks is in What to Do After a Liver Cleanse. Alcohol adds its own load on top, covered in Can You Drink Alcohol on a Liver Cleanse?

The full plan comes with the cleanse

Love Your Liver is Dr. Jarod's 21-day guided liver cleanse, and it's self-paced. The full meal plan, supplement schedule, shopping list and daily texts come with the cleanse. Your supplements ship to your door, and Day 1 starts the moment you tap start.

Prefer to start with a conversation? Dr. Jarod runs functional medicine and lab testing at Crown Chiropractic in Fort Myers. Call (239) 441-2275 to book a consultation.

Sources

• Dr. Jarod Ward, Crown Chiropractic. Liver episode on YouTube.
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