Up to 20% of American adults have some degree of fatty liver disease, a condition that used to occur almost exclusively in people who drink too much alcohol. The increase can be blamed on the twin epidemics of obesity and diabetes, reports the January 2011 issue of the Harvard Health Letter.

One leading theory is that the condition starts when muscle, fat, and liver cells stop responding normally to insulin. This so-called insulin resistance is a hallmark of obesity and diabetes. Insulin resistance also increases the amount of fat molecules circulating in the blood. The accumulation of these molecules inside liver cells can lead to liver inflammation and damage. This is called nonalcoholic steatohepatitis (NASH).

NASH is often a relatively stable condition with few if any symptoms. But it can also lead to serious damage to the liver and its function — a condition called cirrhosis.

A liver biopsy is the only way to definitively diagnose fatty liver disease or NASH. In most cases, weight loss is the only recommended treatment. As people lose weight, the fatty liver becomes less fatty.

The Harvard Health Letter notes that there are two bright spots about fatty livers. First, most cases don’t result in serious liver disease. Second, the treatment is to lose weight  —and that will benefit many other parts of the body besides the liver.

Read the full-length article: "When the liver gets fatty"