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

The liver is the second largest organ in the body. Its function is to process everything we eat or drink and filter any harmful substances from the blood. This process is interrupted if too much fat is in the liver. Fatty liver is when fat accounts for more than 5 to 10 percent of your liver’s weight. View a BodyMap of the liver and learn more about its function.

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.

Fatty liver is a reversible condition that can often be resolved with lifestyle modifications. In many cases, fatty liver has no symptoms. It doesn’t usually cause permanent damage unless it progresses.

Fatty liver is a common condition, affecting around 10 to 20 percent of Americans without cirrhosis or inflammation. Most cases of fatty liver are detected in people between ages 40 and 60, according to the American Liver Foundation.

Fatty liver can become harmful to the liver if its underlying cause isn’t recognized and treated.

Fatty liver typically has no associated symptoms. You may experience fatigue or vague abdominal discomfort. Your liver may become slightly enlarged, which your doctor can detect during a physical exam.

However, excess fat in the liver can cause inflammation. If your liver becomes inflamed, you may have symptoms such as:

• a poor appetite
• weight loss
• abdominal pain
• physical weakness
• fatigue
• confusion

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

• an enlarging, fluid-filled abdomen
• jaundice of the skin and yellowing of the eyes
• confusion
• a tendency to bleed more easily

The most common cause of fatty liver is alcoholism and heavy drinking. In many cases, doctors don’t know what causes fatty liver in people who don’t drink much alcohol.

Fatty liver develops when the body creates too much fat or cannot metabolize fat fast enough. The excess fat is stored in liver cells where it accumulates to form fatty liver disease. Eating a high-fat, high-sugar diet may not directly result in fatty liver, but it can contribute to it.

Besides alcoholism, other common causes of fatty liver include:

• obesity
• hyperlipidemia, or high levels of fats in the blood
• diabetes
• genetic inheritance
• rapid weight loss
• side effect of certain medications, including aspirin, steroids, tamoxifen (Nolvadex), and tetracycline (Panmycin)

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. NAFL is diagnosed when more than 10 percent of the liver is fat.

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 will disappear. However, if excessive alcohol use continues, cirrhosis may develop. Read more about the effects of alcohol on the body.

Nonalcoholic steatohepatitis (NASH) and alcoholic steatohepatitis

When enough fat builds up, it will cause the liver to swell. If the original cause is not from alcohol, it’s called nonalcoholic steatohepatitis (NASH). This disease can impair liver function.

Symptoms can be seen with this disease. These include:

• appetite loss
• nausea
• vomiting
• abdominal pain
• jaundice

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

Acute fatty liver of pregnancy

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

Symptoms begin in the third trimester. These include:

• persistent nausea and vomiting
• pain in the upper-right abdomen
• jaundice
• general malaise

Women who are pregnant will be screened for this condition. Most women improve after delivery and have no lasting effects.

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. Studies have shown that a high-choline diet is associated with a lower risk of fatty liver disease.

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

• excessive alcohol use
• taking more than the recommended doses of certain over-the-counter medications, such as acetaminophen (Tylenol)
• pregnancy
• high cholesterol
• high triglyceride levels
• malnutrition
• metabolic syndrome

Physical exam

If your liver is inflamed, your doctor can detect it by examining your abdomen for an enlarged liver. 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 on a routine blood test. This doesn’t confirm a diagnosis of fatty liver. 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. The fat will show up as a white area on the ultrasound image. 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 any further damage.

Liver biopsy

In a liver biopsy, your doctor will insert a needle into the liver to remove a piece of tissue for examination. Your doctor will give you a local anesthetic to lessen the pain. This is the only way to know for certain if you have fatty liver. The biopsy will also help your doctor determine the exact cause.

There isn’t a medication or surgery to treat fatty liver. Instead, your doctor will offer recommendations to reduce your risk factors. These recommendations include:

• limiting or avoiding alcoholic beverages
• managing your cholesterol and reducing your intake of sugar and saturated fatty acids
• 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 certain types of food from your diet. Reducing the number of calories you eat each day can help you lose weight and heal your liver.

You can also reverse fatty liver disease by reducing or eliminating fatty foods and foods high in sugar from your diet. Choose healthier foods such as fresh fruits, vegetables, and whole grains. Replace red meats with lean animal proteins such as chicken and fish.

Many cases of fatty liver don’t develop into liver disease. The liver can repair itself, so if you take the necessary steps to treat high cholesterol, diabetes, or obesity, you can reverse your fatty liver. If you’re a heavy drinker, stopping drinking or limiting your alcohol intake to 1-2 beverages a day may heal your liver completely. A liver biopsy can help your doctor identify permanent liver damage, as well as determine the severity of damage and the best way to treat it.

If fatty liver persists and is not reversed, it can progress into liver disease and cirrhosis. The progression to cirrhosis is dependent on the cause. In alcoholic fatty liver, continuing to drink alcohol in excess can lead to rapid development of cirrhosis and subsequent 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 are diagnosed with steatohepatitis, you have a higher chance of developing scarring and liver disease. Twenty-five percent of people with steatohepatitis will develop cirrhosis within a decade.

If a fatty liver has progressed to cirrhosis, the risk of liver failure and death rises significantly. Half of those with cirrhosis from fatty liver disease will develop signs of liver failure. If this happens, the survival rate is often no more than two years.