A surprisingly common liver disease affects millions in the US. What to know, according to a doctor

By Katia Hetter, CNN

(CNN) — A health condition many people have never heard of has become one of the most common liver diseases in the United States.

Metabolic dysfunction–associated steatotic liver disease, or MASLD, often develops quietly, so many people do not realize they have it until it is more advanced and signs show up in blood tests or ultrasounds. Even then, the disease can be hard to detect.

What is MASLD, and why is it becoming so common? How is it diagnosed if most people do not notice the symptoms? Who is most at risk? Can the condition be slowed or reversed, and what treatments exist? And what steps can people take now to protect their liver health?

To guide us through these questions, I spoke with CNN wellness expert Dr. Leana Wen. She is an emergency physician and adjunct associate professor at George Washington University. Wen previously served as Baltimore’s health commissioner.

CNN: What is metabolic dysfunction–associated steatotic liver disease, or MASLD, and why is it becoming so common?

Dr. Leana Wen: MASLD happens when too much fat builds up in the liver of people who often have underlying metabolic problems, such as obesity and type 2 diabetes. It is not caused by heavy alcohol use. In the past, MASLD was called nonalcoholic fatty liver disease, and people may still hear of the condition being referred to by this name or its abbreviation, NAFLD.

Experts now consider MASLD to be the most common chronic liver disease worldwide. It affects 30% to 40% of the adult population globally, including approximately 60% to 70% of people with type 2 diabetes and 70% to 80% of people with obesity, and roughly 1 in 3 adults in the United States, according to a recent review in JAMA. As rates of obesity and diabetes have risen, MASLD has increased along with them.

Most people with MASLD will not see their illness progress to severe liver disease, but a significant proportion will develop inflammation, scarring, cirrhosis, liver failure or liver cancer over many years. The condition has already become a leading reason for liver transplantation in certain populations groups.
Moreover, this disease is closely associated with other consequences of diabetes and obesity, such as heart disease, stroke and certain cancers, so MASLD is a signal that the whole body is under metabolic strain, not just the liver.

CNN: Are there specific symptoms people should watch for?

Wen: Most people with MASLD have no symptoms in the early stages, which is why it often goes undiagnosed. Some may feel more tired than usual or notice vague discomfort or a feeling of fullness on the upper right side of the abdomen, but these signs are nonspecific and easy to overlook.

As liver damage progresses to more advanced scarring or liver failure, symptoms become more obvious. They can include yellowing of the skin or eyes, dark urine, swelling in the legs or abdomen, easy bruising, confusion or severe fatigue. At that point, the liver disease is already advanced, which is why it’s important to diagnose the condition long before these symptoms appear.

CNN: How is MASLD diagnosed if most people do not notice symptoms?

Wen: In many cases, doctors first suspect MASLD when routine blood tests show mildly abnormal liver enzymes or when an imaging study done for another reason, such as an abdominal ultrasound, shows that the liver looks “fatty.” Because most people don’t have symptoms, the diagnosis depends on health care providers putting together these clues and checking for metabolic risk factors — namely excess weight, diabetes or prediabetes, high blood pressure and high cholesterol.

Once physicians identify fat in the liver and rule out other causes, such as viral hepatitis or heavy alcohol use, they check for any liver damage or scarring. They may order specialized imaging, and in certain circumstances, a liver biopsy may be performed. One of the key messages from the JAMA article is that primary care clinicians caring for people with metabolic risk factors should be thinking about liver health and consider screening with noninvasive tools, rather than waiting until symptoms develop.

CNN: Who is most at risk for MASLD?

Wen: It’s most often seen in adults who have metabolic risk factors. While obesity is a major risk factor, the condition doesn’t only affect people who appear overweight. Smaller “metabolically unhealthy” individuals also can develop MASLD.

Older age is another risk factor, with incidence higher among those 50 and above, though the condition also can affect children: Close to 10% of children ages 2 to 19 have MASLD, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

In the United States, the condition is most prevalent among Hispanic people, followed by non-Hispanic Whites and Asian Americans and less common among non-Hispanic Black individuals, the federal agency notes.

CNN: Can MASLD be slowed or reversed, and what treatments exist?

Wen: The good news is that in many people, MASLD can be improved or even reversed, especially if it is caught early.

Weight loss is the cornerstone of treatment and can significantly reduce liver fat and inflammation. Regular physical activity, such as brisk walking most days of the week, also helps improve insulin sensitivity and reduce liver fat.

Until recently, there were no medications specifically approved for MASLD. That is beginning to change. The US Food and Drug Administration has approved two drugs for MASH (metabolic dysfunction–associated steatohepatitis), the more advanced form of MASLD that includes liver inflammation and scarring. These two medicines, Rezdiffra (resmetirom) and Wegovy (semaglutide), are meant to be used along with, not instead of, lifestyle changes. There is still no drug that can fully “cure” MASLD, so diagnosing early and preventing progression remain crucial.

CNN: What steps can people take now to protect their liver health?

Wen: For most people, protecting the liver from MASLD is the same as protecting overall metabolic health. Maintaining or working toward a healthy weight, being physically active, and eating a healthy diet with lean proteins, whole grains and vegetables, as well as one that is low in added sugars and ultraprocessed foods, all help.

If you have type 2 diabetes, high blood pressure or high cholesterol, it is important to work with your clinician to control these conditions. Ask specifically whether your liver health has been checked. Simple blood tests can identify people who might benefit from further evaluation. And consider other steps to improve liver health, including avoiding excessive alcohol intake and staying up-to-date on hepatitis vaccines that protect the liver.

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