Fatty liver disease involves the buildup of fat in the liver. This triggers inflammation, which over time can lead to serious complications, including cirrhosis, liver cancer and the need for a liver transplant.

Fat accumulation in the liver can have several causes. People who drink heavily may develop alcoholic fatty liver disease. Certain drugs, environmental toxins and hepatitis C virus genotype 3 can also lead to liver fat buildup. When it occurs in people who do not drink much, the condition is known as non-alcoholic fatty liver disease (NAFLD) or its more severe form, non-alcoholic steatohepatitis (NASH).

Fatty liver disease is associated with metabolic syndrome, a cluster of conditions—increased fat around the waistline, high blood pressure, elevated blood sugar and abnormal blood lipid levels—that raise the risk of cardiovascular disease. In fact, some experts now use the term metabolic-associated fatty liver disease (MAFLD) to emphasize the connection. Although fatty liver disease is most common in people with obesity, it can occur in lean people too.

NAFLD and NASH are responsible for a growing burden of advanced liver disease in the United States and worldwide. It is estimated that up to a third of American adults have fatty liver disease, and the proportion is rising. The condition is also becoming more common among children and adolescents.

Liver Disease Progression

Fat buildup in the liver usually progresses gradually. NAFLD often has no symptoms during its early stages, and there are currently no simple tests for fatty liver disease. Over time, fat in the liver can cause worsening inflammation and liver damage. As the liver tries to repair itself, it produces scar tissue, a process known as fibrosis. As fibrosis worsens, people may experience fatigue, gastrointestinal problems and abdominal pain. Noninvasive imaging methods can reveal fat and scar tissue in the liver, but a liver biopsy is the most accurate way to diagnose liver inflammation, fibrosis and NASH.

Cirrhosis is the most severe stage of fibrosis. People with the most advanced liver disease—known as decompensated cirrhosis—may develop fluid accumulation in the abdomen (ascites), bleeding blood vessels in the esophagus or stomach, and confusion and other mental symptoms (hepatic encephalopathy). Cirrhosis is a risk factor for hepatocellular carcinoma, the most common type of liver cancer. Now that hepatitis B can be prevented with a vaccine and hepatitis C can easily be cured with antiviral medications, fatty liver disease has become a leading reason for liver transplants.

Managing Fatty Liver Disease

Overweight or obesity, an unhealthy diet and a lack of physical activity are some lifestyle factors that play a role in the development of fatty liver. There are currently no approved medical treatments for fatty liver disease. Many experimental drugs for NAFLD and NASH are being studied, but progress has been slow, and several candidates have failed to improve fat buildup and fibrosis in clinical trials.

In the meantime, lifestyle changes are the main approach for managing NAFLD and NASH. These include eating a healthy diet, exercising and losing weight. Experts recommend getting at least 150 minutes of moderate physical activity each week. Even a small amount of weight loss—as little as 5%—can lead to improvement. 

Healthy Liver Tips

  • Eat a healthy, balanced diet.
  • Maintain a healthy weight.
  • Avoid or cut down on alcohol.
  • Exercise regularly.
  • Get enough good-quality sleep.
  • Get vaccinated against hepatitis A and B.
  • Follow medical advice for keeping diabetes and high cholesterol in check.
  • Get regular follow-up tests to monitor for worsening liver disease.