Fatty liver disease, also called non-alcoholic fatty liver disease (NAFLD), and its more severe form, non-alcoholic steatohepatitis (NASH), are conditions caused by fat accumulation in the liver, known as hepatic steatosis. Heavy alcohol consumption can also lead to fat accumulation, a condition known as alcoholic fatty liver disease.
When fat accumulates, the liver becomes inflamed and damaged, leading to fibrosis (buildup of scar tissue), cirrhosis (advanced scarring), hepatocellular carcinoma (HCC), the most common type of primary liver cancer and liver failure that necessitates a liver transplant.
In many cases, liver fat accumulation is associated with obesity and diabetes, so it is sometimes referred to as metabolic-associated fatty liver disease (MAFLD).
Fatty liver disease is becoming the most common liver disease in the United States and worldwide, coinciding with rising rates of obesity. Estimates suggest that around one third of U.S. adults have NAFLD. What’s more, children and adolescents are increasingly being diagnosed with fatty liver disease as childhood obesity becomes more common. Now that vaccination can prevent hepatitis B and antiviral therapy can cure hepatitis C, fatty liver disease is a leading cause of cirrhosis and liver cancer.
Last Reviewed: January 27, 2023