Nonalcoholic fatty liver disease, often called NAFLD, is a liver problem that affects people who drink little to no alcohol. In NAFLD, too much fat builds up in the liver. It is seen most often in people who are overweight or obese.

NAFLD 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. NAFLD ranges in severity from hepatic steatosis, called fatty liver, to a more severe form of disease called nonalcoholic steatohepatitis (NASH).

NASH causes the liver to swell and become damaged due to the fat deposits in the liver. NASH may get worse and may lead to serious liver scarring, called cirrhosis, and even liver cancer. This damage is like the damage caused by heavy alcohol use.