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. Now that hepatitis B can be prevented with a vaccine and hepatitis C can be cured with antivirals, non-alcoholic fatty liver disease (NAFLD) and its more severe form, non-alcoholic steatohepatitis (NASH), are leading causes of advanced liver disease in the United States and worldwide.
Experts estimate 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. Latinos have a higher rate of NAFLD than African Americans or whites. Fatty liver disease is common among people living with HIV—perhaps more so than among the general population.
Fat accumulation in liver cells, known as steatosis, can have several causes. NAFLD and NASH are increasingly recognized as part of metabolic syndrome, a cluster of conditions that raise the risk for cardiovascular disease that is also known as metabolic-associated fatty liver disease (MAFLD). NAFLD is often linked to obesity—especially excess visceral abdominal fat—and it often occurs together with insulin resistance, type 2 diabetes and abnormal cholesterol and triglyceride levels. People who drink heavily may develop alcoholic fatty liver disease. Some research suggests that persistent inflammation due to chronic HIV infection and the side effects of certain antiretroviral drugs may contribute to fatty liver disease as well.
NAFLD usually progresses gradually, as fat buildup triggers inflammation that leads to worsening liver damage. As the liver tries to repair itself, it can develop scar tissue, known as fibrosis; cirrhosis is the most advanced stage of fibrosis. People with cirrhosis are at risk of developing hepatocellular carcinoma—the most common type of liver cancer—and end-stage liver failure.
Managing Fatty Liver Disease
NAFLD often has no symptoms during its early stages. But as fibrosis worsens, people may experience fatigue, gastrointestinal problems and upper abdominal pain. Those with advanced liver disease may develop jaundice (yellowing of the skin and eyes), fluid accumulation in the abdomen (ascites), bleeding blood vessels in the esophagus or stomach and a brain disorder known as hepatic encephalopathy.
There are currently no approved medications for fatty liver disease, and lifestyle changes are the mainstay of prevention and management. Excess weight, poor diet and lack of exercise play a key role in the development of NAFLD. Eat a diet rich in fruits and vegetables, whole grains and lean protein, and limit processed foods and those that are high in fat and added sugar. Aim to move more and sit less throughout the day. Federal guidelines recommend at least 150 minutes of moderate aerobic activity per week, but any amount of physical activity is better than none. Even a small amount of weight loss—as little as 5%—can improve fatty liver disease.
Research is underway to develop medications to treat NAFLD and NASH, but progress has been slow. Several experimental drugs that produced favorable biomarker changes in early studies did not significantly improve fibrosis in larger clinical trials. Fat and glucose metabolism, inflammation and fibrosis are complex, and scientists have tried a wide variety of approaches to target these processes. Many experts expect that a combination approach will be needed to successfully manage fatty liver disease.