Non-alcoholic fatty liver disease (NAFLD) is excessive fat build-up in the liver with insulin resistance due to causes other than alcohol use. There are two types; non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH), with the latter also including liver inflammation. Non-alcoholic fatty liver disease is less serious than NASH, and usually does not progress to NASH or to liver cirrhosis. When NAFLD does progress to NASH, it may eventually lead to complications such as cirrhosis, liver cancer, liver failure, or cardiovascular disease.
Being overweight is the strongest risk factor of NAFLD. Other risks include metabolic syndromes (diabetes, obesity, high blood pressure), a diet high in fructose, and older age. NAFLD and alcoholic liver disease are types of fatty liver disease. Treatment for NAFLD is weight loss by dietary changes and exercise. There is tentative evidence for pioglitazone and vitamin E. Bariatric surgery can improve or resolve severe cases. Those with NASH have a 2.6% increased risk of dying per year.
NAFLD is the most common liver disorder in developed countries, affecting 75 to 100 million Americans in 2017. Over 90% of obese, 60% of diabetic and up to 20% normal-weight people develop it. It is estimated that 24% of the worldwide population is affected as of 2017. NAFLD is the leading cause of chronic liver disease, and the second most common reason for liver transplantation in USA and Europe as of 2017. About 12 to 25% of people in USA have NAFLD and 20 to 25% in Europe, while NASH affects between 2 and 12% in USA. The annual economic burden was estimated at US$103 billion in the US in 2016.