Nonalcoholic fatty liver disease (NAFLD) is the buildup of extra fat in liver cells that is not caused by alcohol.

It is normal for the liver to contain some fat; however, if more than 5%–10% percent of the liver’s weight is fat, it’s called a fatty liver (steatosis). The more severe form of NAFLD is called nonalcoholic steatohepatitis (NASH). NASH causes the liver to swell and become damaged and is an increasingly common symptom occurring in obese and overweight children and teens.

As per the American Liver Foundation, NAFLD is the most common form of liver disease in children and has more than doubled over the past 20 years.