Symptoms & Causes of NAFLD & NASH

What are the symptoms of NAFLD and NASH?

Usually, nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are silent diseases with few or no symptoms. You may not have symptoms even if you develop cirrhosis due to NASH.

If you do have symptoms, you may feel tired or have discomfort in the upper right side of your abdomen.

What causes NAFLD and NASH?

Experts are still studying the causes of NAFLD and NASH. Research suggests that certain health conditions make you more likely to develop NAFLD or NASH.

Causes of NAFLD

You are more likely to develop NAFLD—either simple fatty liver or NASH—if you

  • are overweight or obese
  • have insulin resistance 
  • have abnormal levels of fats in your blood, which may include
  • have metabolic syndrome or one or more traits of metabolic syndrome. Metabolic syndrome is a group of traits and medical conditions linked to overweight and obesity. People with metabolic syndrome are more likely to develop type 2 diabetes and heart disease. Experts think NAFLD may be closely linked to metabolic syndrome. Doctors define metabolic syndrome as the presence of any three of the following:
    • large waist size
    • high levels of triglycerides in your blood
    • low levels of HDL cholesterol in your blood
    • high blood pressure
    • higher than normal blood glucose levels
  • have type 2 diabetes

Research also suggests that certain genes may make you more likely to develop NAFLD. Experts are still studying the genes that may play a role in NAFLD.

In NAFLD, people have a buildup of fat in the liver that is not caused by alcohol use. If you have a history of heavy alcohol use and fat in your liver, your doctor may determine that you have alcoholic liver disease instead of NAFLD.

Causes of NASH

Experts are not sure why some people with NAFLD have NASH and others have simple fatty liver. Research suggests that certain genes may play a role.

People with NAFLD are more likely to have NASH if they have one or more of the following conditions:

  • obesity, especially with a large waist size
  • high blood pressure
  • high levels of triglycerides or abnormal levels of cholesterol in their blood
  • type 2 diabetes
  • metabolic syndrome

Less common causes of NAFLD and NASH

Less common causes of NAFLD and NASH include

A study funded by the National Institute of Diabetes and Digestive and Kidney Diseases found that people who had surgery to remove their gallbladder were more likely to develop NAFLD. More research is needed on the link between gallbladder removal and NAFLD.

November 2016
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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. The NIDDK translates and disseminates research findings through its clearinghouses and education programs to increase knowledge and understanding about health and disease among patients, health professionals, and the public. Content produced by the NIDDK is carefully reviewed by NIDDK scientists and other experts.

The NIDDK would like to thank:
Anna Mae Diehl, M.D., Duke University Medical Center, and Brent A. Tetri, M.D., Saint Louis University