One of the most serious results of overeating, a condition known as non-alcoholic fatty liver disease (NAFLD), is on the rise, according to gastroenterologists at Duke University Medical Center. While there is no confirmed cause of NAFLD, many experts believe that weight loss and increased physical activity are good starting points to help prevent or slow the progress of the condition. Anna Mae Diehl, chief of gastroenterology at Duke, said that NAFLD has become much more widespread as the obesity crisis has worsened.
“By studying over 12,000 people, we demonstrated that probably about 20 percent of people have an elevated liver enzyme that can’t be explained by anything other than NAFLD,” she said.
Despite the significant presence of NAFLD in the U.S. population, the condition has been relatively unknown and understudied compared to other causes of liver damage, said Diehl.
“People are very aware of chronic hepatitis C, and we have a fairly good estimate of that from testing volunteer blood donors in the United States,” she said. “The estimates are that somewhere around two percent of the adult population is infected with hepatitis C. But about 20 percent of the U.S. adult population has non-alcoholic fatty liver disease, so NAFLD would be 10 times more common than hepatitis C.”
Experts said the damage done by fat accretion in the liver is similar to that done by excessive alcohol consumption. As the level of fat increases, liver tissue shrinks. This can cause permanent damage to the organ system. A liver that is more than 10 percent fat is at increased risk for developing cirrhosis or even liver cancer.
Blood tests are commonly the first method of diagnosing NAFLD. If the tests indicate the presence of an elevated liver enzyme, ultrasound, CT (computed tomography) scan or MRI (magnetic resonance imaging) is used. After a physician has eliminated other potential causes of a liver problem, including alcohol abuse, the diagnosis must be confirmed by a liver biopsy, in which a needle is inserted into the liver to extract a tissue sample, which is then analyzed.
As for risk factors, Diehl said one of the most common is obesity.
“In people who are not particularly overweight, the risk of having NAFLD if you have an incidentally detected abnormal blood test might only be about 40 to 50 percent. However, if you’re overweight or obese, that risk can be as high as 90 percent. Certainly being overweight increases the likelihood that you’ll have this particular kind of liver disease.
“Many people who are overweight don’t have NAFLD,” Diehl continued. “We’re trying to figure out why that is the case. It appears that there may be some difference in where you carry your fat. People who are ‘apples’ – who have a higher waist-to-hip ratio and carry most of their weight around their middle – have what we call visceral adiposity. That seems to be the bad kind of fat, the kind that’s associated with other complications of obesity such as having high blood pressure or type 2 diabetes or problems with cholesterol. That’s the same kind of fat that’s associated with NAFLD.”
As yet there is no approved medication to treat or cure non-alcoholic fatty liver disease. Diehl said, however, that many individuals can reduce their risk of NAFLD by making some basic lifestyle changes.
“I think we were all praying that there would be a pill, but the unfortunate truth is that it’s probably diet and exercise, at least as a good starting point. You may be genetically challenged, in that you have a certain repertoire of genes that makes you more vulnerable to develop these complications of being overweight. If that is in fact the case, then prudence is probably the better part of valor.”