An Overview of Metabolic Dysfunction-associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as nonalcoholic fatty liver disease or NAFLD) is a type of liver disease that is not caused by alcohol. It typically does not cause symptoms in the early stages, but it can cause health problems due to fat accumulation, inflammation, and scarring in the liver.

MASLD is commonly associated with obesity and diabetes, and it can progress if these conditions are not well controlled or if they are not treated. Progression leads to metabolic dysfunction-associated steatohepatitis (MASH, formerly known as nonalcoholic steatohepatitis or NASH), which is a type of liver failure that causes fatigue and potentially life-threatening metabolic problems. There is no medication that can cure MASLD or MASH, and controlling the associated risk factors is a vital part of minimizing future liver damage.

Symptoms

MASLD develops slowly, over many years. It generally affects adults over the age of 50, although it can occur sooner. You might not notice any symptoms of MASLD at all, or you may experience some mild, vague effects of fatty liver disease (also known as steatotic liver disease).

Symptoms that you may experience if you have MASLD include:

• Fatigue
• Decreased appetite
• Nausea
• Abdominal pain
• Abdominal swelling
• Jaundice (yellowing skin or eyes)
• Yellow or dark urine

Some of these effects are not very noticeable. Diabetes and obesity, which commonly begin before MASLD develops, are also associated with fatigue—making it difficult to notice increasing fatigue caused by MASLD.

Often, people who have fatty liver do not have symptoms until the condition progresses and liver failure occurs.

Complications

A more serious complication of fatty liver, MASH, develops when the liver begins to lose function. MASH produces distressing effects, and it interferes with your ability to metabolize certain foods and medication.

The symptoms that can be associated with MASLD are more common in MASH.

And you are likely to experience additional effects as well, including:

• Diarrhea
• Trouble thinking and concentrating
• Difficulty walking

Eventually, end-stage liver disease, which can impair your ability to function, may develop.

Some or all of these life-threatening conditions can occur in late-stage MASH or MASLD:

• Cirrhosis (hardening of the liver)
• Liver failure
• Liver cancer

Causes

The exact cause of MASLD is not known, but it is usually preceded by certain medical conditions. These conditions interfere with the body's metabolism, and this may cause excess fat to accumulate in the liver.

Risk factors associated with MASLD include:

• Obesity
• Type 2 Diabetes
• Metabolic syndrome 
• High triglyceride and cholesterol levels
• Eating an unhealthy diet (foods that are processed or that do not have many nutrients)

How Liver Damage Occurs in MASLD

When more than 5% to 10% of your liver’s weight is composed of fat, the effects of fatty liver can occur. The liver becomes swollen, and blood flow can be slowed down. A liver which has excess fat is also vulnerable to inflammation, scarring, decreased function, and liver failure.

Inflammation causes scarring in advanced MASLD, which can lead to cirrhosis. Whenever your liver becomes damaged, your body lays down collagen to repair it. Fibrosis (thickening of the liver tissue) then ensues.

Impaired Liver Function

The liver is the largest internal organ in your body. It performs several functions, such as processing everything you eat and drink, detoxifying chemicals (such as medications), controlling blood sugar levels, and helping build immune proteins.

When MASLD interferes with your liver function, health problems can result.

Diagnosis

Fatty liver is often detected incidentally before any symptoms occur. You may have an abdominal imaging test for another reason, and it can show an enlarged liver.

Sometimes MASLD is detected during an unrelated surgical procedure of the abdomen. Your surgeon may notice that your liver appears enlarged and lighter in color than a typical liver. If discovered during surgery, the texture may also be softer than a typical liver.

If you have risk factors for MASLD you may need a diagnostic evaluation so you and your medical team will know if you are developing fatty liver. And if you have started to develop some of the effects, then you may need a diagnostic workup to identify the cause of your symptoms.

Some tests you may have include:

• Blood tests: Liver enzymes can be altered in fatty liver, and these levels can be measured in the blood. Sometimes, liver enzymes are normal until scarring begins to occur.
• Imaging tests: Abdominal ultrasound, computerized tomography (CT), or magnetic resonance imaging (MRI) can often identify an enlarged liver.
• Liver biopsy: A liver biopsy is a sample of the liver tissue. It is obtained with a surgical procedure. The sample is examined under a microscope, and it may show signs of fatty liver disease, an infection, inflammation, cancer, or another condition affecting the liver.

Treatment

There is no cure for MASLD, but there are medications and strategies that can prevent it from developing and that can keep it from progressing if you already have it.

Managing fatty liver includes the following approaches:

• Maintain a healthy weight
• Avoid a high-fat diet
• Keep your blood sugar controlled
• Avoid alcohol
• Do not use medications that are contraindicated for use with liver disease, such as Tylenol (acetaminophen)
• Minimize your consumption of foods that contain preservatives, dyes, and artificial ingredients
• Try to eat a diet that is rich in health-promoting antioxidants, such as vitamin E and vitamin C

There are several herbs associated with improved liver health. Milk thistle, turmeric, and burdock may have detoxifying effects. Herbs have not been proven to work as effective treatments for MASLD, but experts suggest that they may have potential in treating this disease.

Caution With Medications and Supplements

When you have liver disease, it is important that you are cautious when using medications, supplements, and herbs. A number of medications and supplements are harmful to the liver, so be sure to ask your pharmacist if any of your medications—even those that are over-the-counter—can damage the liver.

Products that do not directly harm the liver can be problematic when you have liver disease. Many medications, supplements, and herbs are detoxified by the liver.

Diet

Liver disease can impair your metabolism of food, especially protein and fat. If you have MASLD, you should meet with a dietitian to get advice about managing your diet.

Transplant

A liver transplant can be an option for you if you have major health problems due to MASH, like cirrhosis. This is a major procedure, and it takes a toll on your body—so it isn't necessarily right for everyone. You and your healthcare provider can discuss the risks and benefits of a liver transplant, and whether it would be an option for you.

A Word From Verywell

It can be a shock to learn that you have liver disease, especially if you are not a heavy drinker. Keep in mind that even if you have MASLD or MASH, there are ways to manage your condition. When you follow the recommendations for managing your liver disease, your overall health will undoubtedly improve as well because the strategies—weight loss, eating healthy, natural foods, and blood sugar control—can help prevent many other conditions as well as MASLD and MASH.