What is MASLD?

Metabolic dysfunction-associated steatotic liver disease (MASLD) happens when too much fat builds up in the liver. It is a long-term (chronic) liver disease, which means it develops slowly and may get worse over time.

MASLD is often linked to conditions like obesity, type 2 diabetes and heart disease. These are sometimes called metabolic conditions.

The liver is a large organ found at the top of the abdomen on the right side. It is made up of cells (hepatocytes), blood vessels and bile ducts. The liver has around 500 different jobs.

Find out more about the liver

Your liver is not meant to store extra fat. When fat builds up in the liver, it can cause inflammation (irritation and swelling). Over time, this damages liver cells. In some people, it can progress to a more serious stage where scarring (fibrosis) builds up in the liver. In a small number of people, it can lead to cirrhosis, liver failure or liver cancer.

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How common is MASLD?

MASLD is very common. About 1 in 4 adults in the UK have it. It is also the biggest cause of long-term (chronic) liver disease worldwide.

MASLD can affect anyone, including children. But it becomes more common as people get older. Genetics and ethnic background matter too, with more people of Asian descent being affected. MASLD is also more common in men.

The number of people in the UK with MASLD is increasing. This rise is linked to rising rates of overweight and obesity. About 1 in 20 adults may have more advanced liver scarring.

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What are the different names for MASLD?

MASLD, NAFLD and fatty liver disease are different names for the same condition.

In 2023, an international group of healthcare professionals and patients updated the names for the condition.

If you have more advanced liver disease, you may also hear the term metabolic dysfunction-associated steatohepatitis (MASH). This was previously called non-alcohol related steatohepatitis (NASH). This is simply another way that doctors may refer to more advanced liver scarring.

The new terms aim to:

• better reflect the complexity of the condition
• show that metabolism plays a key role
• avoid terms such as “non-alcoholic” and “fatty”, which some people may find upsetting or judgemental

You might still hear and see both the old and new terms for a while. But knowing the different terms can help make conversations clearer. You can use whichever name you feel most comfortable with. In our information, we use the new terms to help keep things simple.

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What do the different terms mean?

The name MASLD stands for metabolic dysfunction-associated steatotic liver disease. See the table below to understand what the different words mean.

So, in simpler terms, MASLD means fatty liver disease caused by something going wrong with how the body uses and stores energy.

Remember: If you are unsure about terms or medical words it is always ok to ask questions.

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