Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly called nonalcoholic fatty liver disease (NAFLD), is a liver condition that affects people with excess weight, obesity or other metabolic conditions, such as type 2 diabetes, high blood pressure or high cholesterol. In MASLD, too much fat builds up in the liver. MASLD is becoming more common, especially in Middle Eastern and Western nations, as the number of people with obesity rises. It is the most common form of liver disease in the world. MASLD ranges in severity from hepatic steatosis - sometimes called diffuse hepatic steatosis, or formerly fatty liver infiltration or simply fatty liver - to a more severe form of disease called metabolic dysfunction-associated steatohepatitis (MASH), formerly called nonalcoholic steatohepatitis (NASH). MASH causes the liver to swell or enlarge. This is known as hepatomegaly. MASH also causes fat deposits in the liver, which causes liver damage. MASH may get worse and may lead to serious liver scarring, called cirrhosis, or even liver cancer. This damage is like the damage caused by heavy alcohol use. Life expectancy varies depending on whether you have MASLD or MASH. Factors such as scarring and other health conditions also affect how long you can live with MASLD or MASH.