Lifestyle factors often play a role in the development of metabolic dysfunction-associated steatotic liver disease (MASLD, formerly known as non-alcoholic fatty liver disease, or NAFLD) and metabolic dysfunction-associated steatohepatitis (MASH, formerly known as non-alcoholic steatohepatitis, or NASH).

In many cases, the buildup of liver fat is associated with type 2 diabetes and obesity, especially abdominal or visceral fat accumulation, indicated by a large waist circumference. However, lean people can also develop fatty liver disease. 

Many experts consider MASLD part of metabolic syndrome, a cluster of conditions—including high blood pressure, elevated blood sugar, abnormal cholesterol and triglyceride levels and excess fat around the waist—that raise the risk for cardiovascular disease and other health problems.

An unhealthy diet, inadequate physical activity and poor sleep are risk factors for MASLD and MASH. Heavy alcohol consumption can lead to a similar condition, alcohol-related liver disease (ALD).

In many cases, fatty liver disease can have multiple simultaneous causes, for example, obesity plus heavy drinking.

People with hepatitis C virus genotype 3 are more susceptible to fatty liver disease than those with other genotypes. The reasons for this have not yet been determined.

Last Reviewed: November 13, 2023