Nonalcoholic fatty liver disease (NAFLD) is the term for conditions in which fat builds up in the liver in people who drink little or no alcohol. Most people with NAFLD have a type called fatty liver (nonalcoholic fatty liver, or NAFL). In these people, the liver fat doesn't seem to cause damage. Some people have a more serious type called nonalcoholic steatohepatitis (NASH). In NASH, the fat in the liver causes inflammation and damage. Over time, NASH can cause scarring of the liver, which can lead to cirrhosis and liver failure.

Experts don't really know what causes fat buildup in the liver, but being obese seems to increase the risk. Most people who have NAFLD also have one or more of a group of health problems called metabolic syndrome. This includes obesity, high cholesterol, high blood pressure, and insulin resistance or diabetes.

Most people who have NAFLD have no symptoms. It's usually diagnosed with blood tests and imaging tests, such as a CT scan, an ultrasound, or an MRI. A liver biopsy may be done to diagnose scarring or NASH.

Treatment focuses on managing related conditions like diabetes and making lifestyle changes, including losing weight if needed, eating a healthy diet, and being more active. A doctor may prescribe medicines for related conditions or to help with weight loss. Weight-loss surgery may be an option for people who have obesity. If NASH progresses to cirrhosis, a liver transplant may be needed.