Overview and Facts about Fatty Liver Disease (NAFLD and NASH)
Non-alcoholic fatty liver disease (NAFLD) is a disease caused by the buildup of excess fat in a small portion (at least five percent) of liver cells. The liver is responsible for breaking down and removing toxins from your body and aiding in digestive health.
NAFLD is not caused by alcohol abuse, which makes NAFLD distinct from fatty liver disease caused by alcoholism. NAFLD can affect both children and adults; however, the disease is more common in adults. Nonalcoholic steatohepatitis (NASH) is a form of NAFLD, yet NAFLD is the most common form of liver disease in the United States (US).
Approximately 25 to 40 percent of adults in the US have been diagnosed with NAFLD. Of these adults, approximately 60 percent are men. NASH affects about three to 12 percent of adults in the US. Overall, the prevalence of NAFLD and NASH increases as the prevalence of obesity and metabolic syndrome increases.
Symptoms and Signs of Fatty Liver Disease (NAFLD and NASH)
NAFLD and NASH are distinct in that NASH is accompanied by hepatitis or liver inflammation, liver cell damage, and excess fat buildup in the liver. Moreover, NAFLD does not cause further diseases or complications, while NASH can lead to cirrhosis or liver cancer. Simple fatty liver, a form of NAFLD, does not lead to liver cell damage or inflammation.
In general, NAFLD and NASH do not cause any symptoms. If symptoms are present, they may include:
- Loss of appetite
- Pain in the upper right side of the abdomen
- Weight loss
Causes and Risk Factors of Fatty Liver Disease (NAFLD and NASH)
NAFLD occurs in 40-80 percent of persons with type 2 diabetes and in 30-90 percent percent of obese individuals. Thus, individuals who are obese or have obesity-related diseases, such as type 2 diabetes or metabolic syndrome, have an increased risk of developing NAFLD. Therefore, excess body fat may lead to NAFLD and NASH, because the excess body fat gets stored in the liver. High or abnormal blood levels of triglycerides and cholesterol also increase risk of NAFLD and NASH.
Tests and Diagnosis of Fatty Liver Disease (NAFLD and NASH)
To diagnose NAFLD or NASH, doctors begin by assessing your medical history and performing a physical examination to look for signs of an enlarged liver. An assessment of diet and lifestyle is also used to determine potential risk of obesity or metabolic disease.
Blood tests are also used to look for increased levels of two enzymes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which would indicate liver damage. Imaging tests, such as ultrasounds, magnetic resonance imaging (MRI), and computerized tomography (CT) scans, are also used to look for signs of NAFLD and NASH. A small piece of liver tissue may also be removed and examined under a microscope to look for signs of NAFLD or NASH.
Treatment and Care for Fatty Liver Disease (NAFLD and NASH)
Currently, there are no approved medications to treat NAFLD and NASH. However, some studies show that a type 2 diabetes medication called pioglitazone and vitamin E can improve NASH symptoms.
Affected individuals who are overweight or obese are encouraged to exercise and adopt healthy eating habits to reduce the amount of their overall body fat and lose weight. Rapid weight loss through extreme dieting is not recommended and can worsen NAFLD.