Nonalcoholic fatty liver disease (NAFLD) occurs when your liver stores too much fat and it is not related to heavy alcohol use.
There are two types of NAFLD:
People most often have one type of NAFLD, though sometimes, people with one form of NAFLD can later be diagnosed with another. Experts are not sure why some people who have NAFLD have simple fatty liver while others progress to nonalcoholic steatohepatitis.
Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis are thought of as “silent diseases,” meaning they have few or no symptoms.
Even if nonalcoholic steatohepatitis causes you to develop cirrhosis, you still may not have any symptoms.
Possible symptoms include:
Once cirrhosis is advanced, you can develop symptoms such as:
A liver transplant may be needed if your liver disease becomes this advanced.
The reasons behind what causes nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are still being studied.
Certain conditions, or health problems, may put you at higher risk for developing NAFLD or NASH. Researchers have found that certain genes may make you more likely to develop nonalcoholic fatty liver disease and explain why some NAFLD patients have nonalcoholic steatohepatitis while others have simple fatty liver.
If you have NAFLD, you are more likely to have NASH if you also have one or more of the following:
Less common causes of NAFLD and NASH include:
Your gastroenterologist will review your health and medication history, do a physical exam and order certain tests to find out if you have nonalcoholic fatty liver disease or nonalcoholic steatohepatitis (NAFLD or NASH).
Your gastroenterologist will ask if you have had certain health conditions:
Your doctor will also ask about what kinds of food you eat and lifestyle factors, which can increase your chances of developing NAFLD and NASH:
Your gastroenterologist may also ask how much alcohol you drink to help decide if alcohol is the cause of fat in your liver and you are showing signs of alcoholic liver disease instead of NAFLD.
Your gastroenterologist will check your weight and height to figure out your body mass index (BMI) to confirm if you are underweight, normal weight, overweight or have obesity. He or she will also look for signs of NAFLD or NASH:
Your doctor may order blood tests, imaging tests and perhaps a liver biopsy to find out if you have nonalcoholic fatty liver disease or nonalcoholic steatohepatitis.
These tests can be performed in an outpatient center or hospital. Ultrasounds are often performed in radiology departments and transient elastography can often be performed in a provider’s office.
These imaging tests can show fat in your liver, but they cannot show swelling of your liver or fibrosis (scarring), or whether you have simple fatty liver or NASH. If you have cirrhosis, the imaging tests may show nodules, or lumps, on your liver.
During a liver biopsy, which can be performed at a hospital or an outpatient center, your gastroenterologist will take a tiny piece of tissue from your liver. You will be told how to get ready for the biopsy beforehand. A pathologist (a doctor who specializes in looking at tissues to diagnose diseases) will then look at the tissue under a microscope to look for signs of damage or disease.
A liver biopsy is the only way to find liver inflammation, or swelling, and damage to diagnose nonalcoholic steatohepatitis. This test is not recommended for everyone with nonalcoholic fatty liver disease. A liver biopsy will only be done if you are more likely to have NASH, or if other tests show signs of advanced liver disease or cirrhosis. Sometimes, results of the other testing, such as transient elastography, will help to decide if you are more likely to have NASH and if you would benefit from a liver biopsy.
Your doctor may recommend weight loss to treat nonalcoholic fatty liver disease and nonalcoholic steatohepatitis (NAFLD and NASH). Weight loss can help reduce fat in the liver, inflammation (swelling) and fibrosis (scarring).
If you are overweight or have obesity, losing weight by making healthy food choices, limiting portion sizes and being physically active can improve NAFLD and NASH. Losing 3-5% of your body weight can lessen the amount of fat in the liver. To reduce liver swelling, you may need to lose up to 10% of your body weight. Doctors recommend slowly losing 7% of your body weight or more over the course of one year. Rapid weight loss through fasting (eating and drinking nothing except water) can make NAFLD worse.
Your gastroenterologist may suggest that you meet with a nutritionist or knowledgeable dietician to talk about and improve your diet. Changing your diet may include eating less fat to help prevent or treat nonalcoholic fatty liver disease or nonalcoholic steatohepatitis.
Fats are high in calories and increase your chance of having obesity. Replacing saturated fats and trans fats in your diet with monounsaturated fats and polyunsaturated fats, such as omega-3 fatty acids, may help lessen your chance of heart disease if you have NAFLD. Four types of fats are:
Your gastroenterologist or nutritionist may also suggest other dietary changes to help treat nonalcoholic fatty liver disease and nonalcoholic steatohepatitis:
Always speak with your doctor and a nutritionist or knowledgeable dietitian before making changes to your diet, and to help you make a plan you can follow. They may suggest diet plans such as a:
If you have severe obesity—a body mass index (BMI) of 35 to 40 or more—and have not been able to lose or maintain weight loss, your gastroenterologist may suggest bariatric surgery, an operation that helps you lose weight by making changes to your digestive system. Bariatric surgery also may be an option if you have serious health problems, such as type 2 diabetes or sleep apnea, related to having obesity. Learn more about bariatric surgery and other weight loss treatments on our patient education page about obesity.
Currently, there are no drugs that have been approved to treat nonalcoholic fatty liver disease and nonalcoholic steatohepatitis, but researchers are studying medicines that may improve these conditions.
While some studies have shown that supplements may help improve NAFLD or NASH, for safety reasons, always speak with your health care provider before using dietary supplements, such as vitamins, or any complementary or alternative medicines or medical practices. Some herbal remedies can cause more damage your liver.
Researchers are studying many aspects of nonalcoholic fatty liver disease and nonalcoholic steatohepatitis through clinical trials, which include:
You can view a filtered list of clinical studies on NAFLD and NASH that are federally funded, open and recruiting at www.ClinicalTrials.gov. Always talk with your health care provider first before participating in a clinical study.
Support groups are available to help you through your diagnosis. Learn more at the American Liver Foundation website.
Most people with nonalcoholic fatty liver disease have simple fatty liver and people with simple fatty liver typically don’t develop complications. However, people with nonalcoholic steatohepatitis have an increased chance of dying from liver-related causes. For example, if cirrhosis develops and progresses to liver failure, you may need a liver transplant. Studies also suggest that people with NAFLD have a greater chance of developing cardiovascular disease, which is the most common cause of death in people who have either form of NAFLD.
It is important to work with your doctor and other health care providers to monitor your condition and make any needed modifications to your diet or daily habits, as well as follow any recommendations to gradually lose weight if you are overweight or have obesity. You may be able to prevent NAFLD and NASH by eating a healthy diet, limiting your portion sizes and maintaining a healthy weight.