When fat makes up more than 5 or 10 percent of a liver's weight, it has crossed the line from being a healthy liver to a fatty liver. If this is the case, alcoholic or nonalcoholic liver disease may have set in, according to WebMD.
Alcoholic liver disease, or ALD, results from abuse or overuse of alcohol. In the United States, more than 15 million people drink to excess as of 2015, and at least 90 percent of them develop a fatty liver. This can set in after consuming moderate to large amounts of alcohol. Genetics have a strong effect on alcoholic liver disease, as genes can influence alcohol consumption habits as well as one's potential for developing alcoholism. Genes can also influence the liver enzymes that metabolize alcohol, notes WebMD.
Nonalcoholic fatty liver disease, or NAFLD, is the most frequent cause of chronic liver disease in the United States, and it takes on two forms: fatty liver and nonalcoholic steatohepatisis, or NASH. NASH can cause permanent liver damage over time, as the organ grows and scar tissue replaces some of the healthy cells in a process called cirrhosis. This keeps the liver from functioning correctly and can cause liver cancer, liver failure and even liver-related fatality. Fatty liver is not a serious condition if it does not lead to damage or inflammation, but those with fatty liver have an elevated risk of severe damage, states WebMD.