Fatty liver, or hepatic steatosis, is a term that describes the buildup of fat in the liver. It’s normal to have small amounts of fat in your liver, but too much can become a health problem.

The liver is the second largest organ in the body. It’s responsible for a wide variety of functions, including processing everything we eat and drink, and filtering harmful substances from the blood. Too much fat in the liver can lead to long-term liver damage. View a BodyMap of the liver and learn more about its function.

Early stage fatty liver is diagnosed when the proportion of liver cells that contain fat is more than 5 percent. This is often diagnosed by looking at small samples taken from the liver under the microscope. Ultrasounds, CT scans, and MRI scans can also help evaluate the fat content of the liver.

The liver commonly repairs itself by rebuilding new liver cells when the old ones are damaged. When there’s repeated damage to the liver, permanent scarring takes place. This condition is called cirrhosis. In mild forms, fatty liver can be a reversible condition that may improve with lifestyle modifications such as diet changes, weight loss, and increased physical activity. In many cases, fatty liver has no symptoms.

Unfortunately, fatty liver is becoming a more common condition, currently affecting around 20 to 30 percent of Americans. Most cases of fatty liver that are associated with inflammation are detected in people between ages 40 and 60, according to the American Liver Foundation.

Fatty liver becomes harmful to the liver when it progresses. Liver inflammation (steatohepatitis) can lead to liver scarring, liver cancer, and end-stage liver disease.

Fatty liver typically has no associated symptoms. However, research has shown that about 20 percent of people with fatty liver inflammation progress to worse conditions. If this occurs you may experience fatigue or abdominal discomfort. Your liver may become slightly enlarged, which your doctor may be able to detect during a physical exam.

It’s believed that the excess fat in the liver, along with certain medical conditions, increases inflammation. If your liver becomes inflamed, you may have symptoms such as:

If fatty liver progresses to cirrhosis and liver failure, symptoms can include:

The most common cause of fatty liver is alcohol use disorder and heavy drinking. In many cases, it’s much less clear what causes fatty liver in people who don’t drink much alcohol. However, higher body weight, a high processed sugar diet, high triglycerides, diabetes, low physical activity, and genetics all play a role.

Fatty liver develops when the body creates too much fat or cannot metabolize fat efficiently enough. The excess fat is stored in liver cells where it accumulates and causes fatty liver disease.

Besides alcohol use disorder, other common causes of fatty liver include:

  • obesity
  • hyperlipidemia, or high levels of fats in the blood, especially high triglycerides
  • diabetes
  • genetic inheritance
  • rapid weight loss
  • side effects of certain medications, including methotrexate (Trexall), tamoxifen (Nolvadex), amiodorone (Pacerone), and valproic acid (Depakote)

There are two basic types of fatty liver: nonalcoholic and alcoholic.

Nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) develops when the liver has difficulty breaking down fats, which causes a buildup in the liver tissue. The cause is not related to alcohol. NAFLD is diagnosed when more than 5 percent of the liver is fat.

Nonalcoholic steatohepatitis (NASH)

Nonalcoholic steatohepatitis (NASH) is a type of NAFLD. As fat builds up, it can cause inflammation. Once more than 5 percent of the liver is fat and inflammation is also present, the condition is known as NASH.

Symptoms of this condition are related to inflammation and worsening liver function. These can include:

If left untreated, steatohepatitis can progress to permanent scarring of the liver, liver cancer, and eventual liver failure.

Acute fatty liver of pregnancy

Acute fatty liver is a rare and potentially life-threatening complication of pregnancy.

Signs and symptoms begin in the third trimester. These include:

  • persistent nausea and vomiting
  • pain in the upper-right abdomen
  • headache
  • jaundice
  • general malaise
  • fatigue
  • decreased appetite

Women who are pregnant with any of these signs or symptoms should be evaluated for this condition. Treatment includes managing any complications and prompt delivery. Most women improve within several weeks after delivery and have no lasting effects.

Alcoholic fatty liver

Alcoholic fatty liver is the earliest stage of alcohol-related liver disease. Heavy drinking damages the liver, and the liver cannot break down fats as a result. Abstaining from alcohol will likely cause the fatty liver to subside. Within six weeks of not drinking alcohol, the fat can disappear. However, if excessive alcohol use continues, inflammation known as alcoholic steatohepatitis may develop, leading to cirrhosis. Read more about the effects of alcohol on the body.

Fatty liver is the buildup of extra fats in the liver. It’s more likely to develop if you’re overweight or obese. Having type 2 diabetes also may increase your risk for fatty liver. Fat accumulation in the liver has been linked to insulin resistance, which is the most common cause of type 2 diabetes.

Other factors that may increase your risk for fatty liver include:

  • low physical activity

Physical exam

If your liver is inflamed, your doctor may be able to detect it by examining your abdomen for an enlarged liver. However, your liver can be inflamed without being enlarged. Let your doctor know if you’ve been experiencing fatigue or loss of appetite. Also, tell your doctor about any history of alcohol, medication, and supplement use.

Blood tests

Your doctor may find that liver enzymes are higher than normal during a routine blood test. This doesn’t confirm a diagnosis of fatty liver, but it does relate to liver inflammation. Further analysis is necessary to find the cause of the inflammation.

Imaging studies

Your doctor may use an ultrasound to detect fat in your liver. Other imaging studies may also be done, such as CT or MRI scans.

Another imaging test similar to ultrasound is a FibroScan. Like an ultrasound, a FibroScan utilizes sound waves to determine the density of the liver and the corresponding areas of fat and normal liver tissue.

Imaging studies can detect fat in the liver, but they cannot help your doctor confirm the extent of damage.

Liver biopsy

A liver biopsy is still considered the best way to determine the severity of liver disease. During a liver biopsy, your doctor will insert a needle into the liver and remove a piece of tissue for examination. They will give you a local anesthetic to lessen the pain.

A liver biopsy is the only way to know for certain the severity of fatty liver or other liver diseases. The biopsy can also help your doctor determine the exact cause.

Research is ongoing into medications that may help treat fatty liver. The first-line of treatment continues to be following recommendations to reduce your risk factors. These recommendations typically include:

  • limiting or avoiding alcoholic beverages
  • managing your cholesterol and reducing your intake of sugars and saturated fats
  • losing weight
  • controlling your blood sugar

If you have fatty liver because of obesity or unhealthy eating habits, your doctor may also suggest that you increase physical activity and eliminate or add certain types of foods to your diet. Reducing the number of calories you eat each day can help you lose weight and heal your liver.

In the early stages, you can improve and reverse fatty liver disease by reducing or eliminating fatty foods and foods high in sugar from your diet. Choose a balanced diet with healthier foods such as fresh fruits, fresh vegetables, whole grains, and healthy fats like those in nuts and avocados. Replace red meats with lean proteins such as soy, chicken, turkey, and fish. Sweetened drinks, juices, and sodas should be avoided.

Most cases of fatty liver don’t progress into other forms of liver disease. The liver can repair itself, so if you take the necessary steps to treat high cholesterol, diabetes, an unhealthy diet, and obesity, you can reverse fatty liver.

If you’re a heavy drinker, stop drinking alcohol or limit your intake to 1 drink or less per day for women and 2 drinks or less per day for men. A liver biopsy can help your doctor identify permanent liver damage, and determine the severity of damage.

If fatty liver persists and is not reversed, it can progress into liver disease, cirrhosis, or cancer. The progression to cirrhosis is dependent on the cause. In alcoholic fatty liver, continuing to drink alcohol in excess can lead to liver failure.

The progression of nonalcoholic fatty liver disease varies, but in most people it does not lead to liver scarring and cirrhosis. However, if you’re diagnosed with steatohepatitis, you have a higher chance of developing scarring and liver disease. Twenty percent of people with steatohepatitis will go on to develop worsening liver disease.

If fatty liver progresses to cirrhosis, the risk of liver failure and death rises significantly. There is also a higher risk for liver cancer and death from heart disease.

Protecting your liver is one of the best ways to prevent fatty liver and its complications. You can start by taking several steps:

  • limit or eliminate alcohol from your diet
  • eat a healthy, balanced diet
  • control diabetes if you have developed the condition
  • aim for at least 30 minutes of exercise most days of the week

By taking these steps, you’ll not only keep your liver healthy but also improve your overall health.