Definition & Facts of NAFLD & NASH in Children

In this section:

What is NAFLD?

Nonalcoholic fatty liver disease (NAFLD) is a condition in which excess fat builds up in the liver. This buildup of fat is not caused by heavy alcohol use. When heavy alcohol use causes fat to build up in the liver, this condition is called alcohol-associated liver disease.

Two types of NAFLD are nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). Children typically develop one type of NAFLD or the other, although sometimes children with one form are later diagnosed with the other form of NAFLD. NAFL is a mild condition, and NASH is a more serious condition.


NAFL is the form of NAFLD in which a child has increased fat in the liver but little or no inflammation or liver damage. NAFL typically doesn’t progress to cause liver damage or complications.


NASH is the form of NAFLD in which a child has inflammation of the liver and liver damage, in addition to fat in the liver. The inflammation and liver damage of NASH can cause fibrosis, or scarring, of the liver. NASH may lead to cirrhosis, in which the liver is scarred and permanently damaged. Cirrhosis can lead to liver cancer.

Experts are not sure why some children with NAFLD have NASH while others have NAFL.

How common is NAFLD in children?

NAFLD is the most common cause of chronic liver disease in children in the United States. Studies suggest that 5% to 10% of children have NAFLD.1 NAFLD has become more common in children in recent decades, in part because childhood obesity has become more common.

Research suggests that 20% to 50% of children with NAFLD have the NASH form of the disease.1

Who is more likely to develop NAFLD?

Children who have certain health problems, including obesity and conditions related to obesity, are more likely to develop NAFLD.

NAFLD is more common in older children than in younger children and more common in boys than in girls.

Although NAFLD occurs in children of all races and ethnicities, it’s most common in Hispanic children and Asian American children, followed by white children. NAFLD is less common in Black children.1

A boy with overweight or obesity in a classroom.NAFLD is more common in older children than in younger children and more common in boys than in girls.

What are the complications of NAFLD?

Children with NAFLD have a greater chance of developing liver complications or other health problems.

Liver complications

The majority of children with NAFLD have NAFL.1 Children with NAFL typically don’t develop liver complications, although they have a higher risk for other health problems such as diabetes.

However, some children with NAFLD have NASH. NASH can lead to liver complications such as cirrhosis and liver cancer. If cirrhosis leads to liver failure, a liver transplant may be needed.

Compared with people who develop NAFLD during adulthood, people who develop NAFLD during childhood are more likely to have NASH and related complications or liver disease as adults. Children with NASH may develop cirrhosis during childhood.2 However, the complications of cirrhosis, such as liver failure and liver cancer, usually arise in adulthood.

Other health problems

Children with NAFLD have a higher risk for certain health problems, including

People with the metabolic syndrome have a greater chance of heart disease, stroke, and hardening of the arteries as adults.


Last Reviewed December 2021
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This content is provided as a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), part of the National Institutes of Health. NIDDK translates and disseminates research findings to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by NIDDK is carefully reviewed by NIDDK scientists and other experts.