Nonalcoholic fatty liver disease is a term used to describe the accumulation of fat in the liver of people who drink little or no alcohol.Nonalcoholic fatty liver disease is common and, for most people, causes no signs and symptoms and no complications.

But in some people with nonalcoholic fatty liver disease, the fat that accumulates can cause inflammation and scarring in the liver. This more serious form of nonalcoholic fatty liver disease is sometimes called nonalcoholic steatohepatitis.At its most severe, nonalcoholic fatty liver disease can progress to liver failure.

Nonalcoholic fatty liver disease usually causes no signs and symptoms. When it does, they may include:

• Fatigue
• Pain in the upper right abdomen
• Weight loss

Nonalcoholic fatty liver disease occurs when your liver has trouble breaking down fats, causing fat to build up in your liver tissue.

Doctors aren’t sure what causes nonalcoholic fatty liver disease. The wide range of diseases and conditions linked to nonalcoholic fatty liver disease is so diverse that it’s difficult to pinpoint any one cause.

Nonalcoholic fatty liver disease can take several forms — from harmless to life-threatening. Forms include:

• Nonalcoholic fatty liver. It’s not normal for fat to build up in your liver, but it won’t necessarily hurt you. In its simplest form, nonalcoholic fatty liver disease can cause excess liver fat, but no complications. This condition is thought to be very common.
• Nonalcoholic steatohepatitis. In a small number of people with fatty liver, the fat causes inflammation in the liver. This can impair the liver’s ability to function and lead to scarring of the liver (cirrhosis).
• Nonalcoholic fatty liver disease-associated cirrhosis. Liver inflammation leads to scarring of the liver tissue. With time, scarring can become so severe that the liver no longer functions adequately (liver failure).

A wide range of diseases and conditions can increase your risk of nonalcoholic fatty liver disease, including:

• Gastric bypass surgery
• High cholesterol
• High levels of triglycerides in the blood
• Metabolic syndrome
• Obesity
• Polycystic ovary syndrome
• Sleep apnea
• Type 2 diabetes
• Underactive thyroid (hypothyroidism)
• Underactive pituitary gland (hypopituitarism)

Tests and procedures used to diagnose nonalcoholic fatty liver disease include:

• Blood tests. Liver function tests, including tests of liver enzymes, may help your doctor make a diagnosis.
• Imaging procedures.Imaging procedures used to diagnose fatty liver disease include ultrasound, computerized tomography (CT) scan and magnetic resonance imaging (MRI).
• Liver tissue testing. If it’s suspected that you have a more serious form of nonalcoholic fatty liver disease, your doctor may recommend a procedure to remove a sample of tissue from your liver (liver biopsy). The tissue sample is examined in a laboratory to look for signs of inflammation and scarring.

Liver biopsy is typically done using a long needle inserted through your skin and into your liver to remove liver cells (needle biopsy).

No standard treatment for nonalcoholic fatty liver disease exists.

Instead, doctors typically work to treat the risk factors that contribute to your liver disease. For instance, if you’re obese, your doctor can help you to lose weight through diet, exercise and, in some cases, medications and surgery.

Your doctor may recommend that you receive vaccinations against hepatitis A and hepatitis B to help protect you from viruses that may cause further liver damage.

To reduce your risk of nonalcoholic fatty liver disease:

• Choose a healthy diet. Choose a healthy plant-based diet that’s rich in fruits, vegetables, whole grains and healthy fats.
• Maintain a healthy weight. If you are overweight or obese, reduce the number of calories you eat each day and get more exercise. If you have a healthy weight, work to maintain it by choosing a healthy diet and exercising.
• Exercise most days of the week. Get an OK from your doctor first if you haven’t been exercising regularly.