"Fatty liver" means just what it says, a liver that contains excessive amounts of fat. In the most severe cases, the liver becomes enlarged and takes on a yellowish hue.

Fatty liver is the most common liver disease in the United States. It affects up to 30% of our population. This is because of obesity. Excess calories that cannot be burned off by exercise are converted to fat. The liver becomes a storehouse for this fat.

Often, diabetes contributes to the fatty liver of obesity. The second leading cause of fatty liver is excessive alcohol consumption. Alcohol interferes with the normal metabolism of fat. This results in a build-up that is deposited in the liver.

Other causes of fatty liver include:

• Medications, such as prednisone and estrogen
• Several rare metabolic disorders, such as Gaucher’s disease
• Severe starvation (oddly enough)

What are the consequences of fatty liver? The spectrum is vast, ranging from "none" to end stage liver disease. The determining factor is whether the fat causes an inflammatory reaction within the liver, a reaction that damages the cells and leads to scarring and cirrhosis, a disease in which normal liver cells are replaced by scar tissue.

People who have fat in their livers without inflammation (called steatohepatosis) are often unaware of their disorder. They are not apt to have any symptoms. A doctor may find a liver a bit enlarged during a physical exam or by blood tests that show mild abnormalities of liver enzymes. An ultrasound will sometimes be used to confirm the suspected diagnosis of fatty liver.

People with fat in their livers plus liver inflammation (called steatohepatitis) may also be free of symptoms, but they are at risk for the gradual loss of liver function due to scarring over the years. A small number of these people will eventually develop cirrhosis.

To distinguish one form of fatty liver from the other, doctors rely upon a liver biopsy. This is a fairly safe procedure. But the real question is whether the information from the biopsy will lead to treatment that will arrest or reverse the inflammation. We have no drug proven to do this. The best recommendation for people with either type of fatty liver is to lose weight. The benefits of losing weight are likely to extend well beyond the health of the liver.