Obesity: Body Fat, the Silent Killer (cont.)

What is nonalcoholic fatty liver disease (NAFLD)?

Nonalcoholic fatty liver disease (NAFLD) refers to a wide spectrum of liver diseases ranging from the most common, fatty liver (accumulation of fat in the liver, also known as steatosis), to Nonalcoholic steatohepatitis (NASH, fat in the liver causing liver inflammation), to cirrhosis (irreversible, advanced scarring of the liver as a result of chronic inflammation of the liver). All of the stages of Nonalcoholic fatty liver disease are now believed to be due to insulin resistance, a condition closely associated with obesity. In fact, the BMI correlates with the degree of liver damage, that is, the greater the BMI the greater the liver damage.

The term Nonalcoholic is used because liver disease due to alcohol can show the same spectrum of liver disease as nonalcoholic fatty liver disease; however, patients with nonalcoholic fatty liver disease do not consume excessive amounts of alcohol.

Alarming statistics about nonalcoholic fatty liver disease

As expected, nonalcoholic fatty liver disease is observed principally in developed countries. In these societies, a sedentary lifestyle and high calorie, sugar, and fat intake lead to a high prevalence of obesity, insulin resistance, and diabetes.

Nonalcoholic fatty liver disease is currently the most common liver disease in the U.S. and worldwide, affecting estimated 10-24% of the world's population. In the U.S., the Centers for Disease Control reports that currently, approximately one half of the U.S. adult populationisoverweight (BMI>25) and one quarter of the U.S. adult population isobese(BMI>30). That means upwards of 29 million Americans have nonalcoholic fatty liver disease, while 6.4 million of these persons have nonalcoholic steatohepatitis (NASH). Even more alarming than these statistics, nonalcoholic fatty liver disease is occurring among children in the U.S.

In most patients nonalcoholic fatty liver disease causes no symptoms. Nonalcoholic fatty liver disease often is discovered when routine blood tests show slightly elevated levels of liver enzymes (ALT and AST) in the blood. Another way in which nonalcoholic fatty liver disease is discovered is when ultrasound examination of the abdomen is done for other purposes, say for looking for gallstones, and fat is found in the liver. In the late stages of non alcoholic fatty liver disease, the development of cirrhosis can lead to failure of the liver, swelling of the legs (edema), accumulation of fluid in the abdomen (ascites), bleeding from veins in the esophagus (varices), and mental confusion (hepatic encephalopathy). Patients with cirrhosis caused by Nonalcoholic fatty liver disease also may be at risk of developing liver cancer (hepatocellular carcinoma, HCC).