What Is MASLD? Understanding Fatty Liver Disease

More than one-third of American adults have MASLD, formerly known as fatty liver disease. Most people don’t realize that they have it, because MASLD rarely causes symptoms.

“It’s severely underdiagnosed—way more underdiagnosed than diabetes is,” said Ju Dong Yang, MD, a hepatology specialist at Cedars-Sinai.

{{providers}}

{{cta-block}}

What Is Fatty Liver Disease (MASLD)?

MASLD is an excess buildup of fat in the liver that can’t be attributed to alcohol intake. The condition is typically caused by unhealthy lifestyle habits.

“Fat accumulates in the liver because of excessive caloric intake and not enough energy expenditure,” Yang said. “It’s the liver manifestation of diabetes, insulin resistance, obesity or high cholesterol.”

Until 2023, MASLD was called nonalcoholic fatty liver disease. The name was changed to better reflect the condition’s connection to metabolic health, which is an indication of how well the body processes food for energy. Signs of good metabolic health include healthy blood-sugar, blood-pressure and cholesterol levels. Poor metabolic health is linked with conditions such as diabetes, obesity and high cholesterol.

When MASLD is diagnosed early, people can usually manage it with healthy lifestyle habits.

Who Is at Risk of Fatty Liver Disease?

People with the following conditions associated with metabolic dysfunction are at increased risk of MASLD:

• Obesity or overweight, with a large waist
• Type 2 diabetes or prediabetes
• Insulin resistance
• High blood sugar
• High low-density lipids (LDL), or “bad” cholesterol
• High triglycerides
• Low high-density lipids (HDL), or “good” cholesterol
• High blood pressure
• Metabolic syndrome

Adults older than 50 are at greater risk of MASLD.

“The prevalence of fatty liver disease gradually increases with age,” Yang said. “People gain weight as they get older. Young people rarely have Type 2 diabetes, but the prevalence goes up in older people.”

Successful treatment with lifestyle modifications, as well as medication, can cool down inflammation.

How MASLD Can Progress If Left Untreated

MASLD rarely causes symptoms until it’s at an advanced stage. People with this silent liver disease may eventually notice fatigue, discomfort in the upper-right abdomen or trouble concentrating.

As MASLD progresses, scar tissue forms within the liver. Eventually, it can lead to cirrhosis when scar tissue in the liver is widespread. Cirrhosis causes permanent liver damage.

If there is inflammation in the liver from excessive fat, it’s called metabolic dysfunction-associated steatohepatitis (MASH) instead of MASLD. Some people with MASH develop cirrhosis, which can cause jaundice, or a yellowing of the skin. Some will develop fluid buildup, causing bloating or swelling in the abdomen and legs.

MASLD also increases liver cancer risk.

“Many patients with MASLD do not develop liver cancer, but the condition increases their risk compared to those who do not have fatty liver disease,” Yang said.

How Doctors Diagnose MASLD

Because MASLD doesn’t cause symptoms, it’s often discovered incidentally.

“A common scenario is someone having abdominal pain, going to the ER, getting a CT scan and doctors seeing excessive fat in the liver,” Yang said.

Doctors sometimes discover MASLD after routine bloodwork. High blood sugar, high LDL cholesterol, low HDL cholesterol and high triglycerides may warrant additional testing. Patients may get a FibroScan, an ultrasound test that measures the amount of liver scarring.

Recent research from Cedars-Sinai investigators is exploring using AI to analyze echocardiograms to identify undiagnosed liver disease during routine heart screenings.

Lifestyle Treatments for MASLD

When someone is diagnosed with MASLD, doctors recommend lifestyle changes, such as:

• ‍A healthy diet. Doctors often recommend Mediterranean-style eating habits. The diet focuses on vegetables, fruits,nuts, beans, whole grains and lean protein such as fish. Red meat, processed foods and sweets should be eaten sparingly. “It has been shown to be helpful for MASLD,” Yang said. “Avoiding excessive amounts of red meat and having more green vegetables is definitely helpful.”‍
• Consistent exercise. People with MASLD should meet the recommended physical activity guidelines: 150 minutes of moderate-intensity aerobic exercise weekly (for example, walking for 30 minutes five days a week) and muscle-strengthening activities twice weekly.‍
• Weight loss. Losing even a small amount of weight can help. Eating differently and exercising more is effective for some people. Others benefit from GLP-1 receptor agonists. “If you lose 5% of your body weight, you will see less fat in the liver,” Yang said. “If you lose7% to 10%, you will see less inflammation in the liver from fat.”‍
• Avoiding alcohol. The liver processes and breaks down alcohol. Avoiding alcohol reduces the liver’s workload and prevents exposure to toxic alcohol metabolites.‍
• Managing metabolic health. Controlling blood sugar, blood pressure and cholesterol helps. “Poorly controlled diabetes, for example, can promote the progression of liver disease,” Yang said.

Medication for MASLD

Doctors don’t prescribe medication for early MASLD. Lifestyle changes tend to be effective for treating the condition at this stage.

For intermediate to advanced MASLD or MASH, doctors may prescribe GLP-1 medications or resmetirom, which helps slow down the liver inflammation and/or scarring process.

How to Protect Your Liver

Some people with MASLD don’t feel sick, so they don’t adopt healthy lifestyle changes. This can lead to serious health problems as the disease progresses.

“People may not recognize the seriousness of MASLD or take it seriously,” Yang said. “Unlike heart attacks or cancer, which can pose an immediate threat to life, MASLD often progresses slowly—but it can eventually lead to life-threatening diseases.”

You can learn your MASLD risk by getting your FIB-4 score. It’s calculated with bloodwork results, estimating the amount of fibrosis, or scarring, in your liver.

If you have questions about your bloodwork results or your risk for MASLD, speak with your doctor. When MASLD is caught early, lifestyle changes can help reverse liver damage.

“Successful treatment with lifestyle modifications, as well as medication, can cool down inflammation,” Yang said. “We sometimes see fibrosis, or scarring, improved. Our goal is always improvement, not just staying static.”