Fatty liver is the buildup of fat in the liver cells. It is a liver condition that may be benign (harmless), but sometimes may contribute to the development of more serious liver conditions, such as inflammation (hepatitis) and scarring of liver tissue (cirrhosis).

There are two major forms of fatty liver: alcoholic and nonalcoholic. When fatty liver occurs alone, it is called steatosis. When it occurs with inflammation or liver cell damage, it is called steatohepatitis. When patients have steatohepatitis but do not drink alcohol, it is called nonalcoholic steatohepatitis (NASH).

In the United States and other Western countries, the main causes of fatty liver include alcohol abuse, obesity and diabetes, a disorder in the body’s ability to use blood sugar. Other causes may include pregnancy and medications such as corticosteroids.

Fatty liver often produces no symptoms. When symptoms are present, they may include fatigue, malaise or abdominal tenderness. If fatty liver develops into a more serious condition, symptoms may include jaundice, weight loss and swelling (edema) in the legs and feet.

Fatty liver is frequently identified while testing for other conditions. A physical examination, medical history and blood tests such as a liver function test may provide some indications of the condition. Fatty liver can be confirmed by removing a small piece of tissue for a liver biopsy.  

Treatment of fatty liver consists of treating its underlying cause. For example, abstinence from alcohol can stop or even reverse fatty liver. Obese people who lose weight and exercise regularly may also reverse this condition. However, any cell death or scarring that results from untreated fatty liver disease is permanent and can impair liver function if severe (e.g., cirrhosis). Other fatty liver treatments that are being studied include vitamins E and C, milk thistle and omega-3 fatty acids.

Some cases of fatty liver cannot be prevented. Others may be prevented by limiting alcohol, maintaining a healthy weight and maintaining normal levels of cholesterol and triglycerides.

Fatty liver is the accumulation of fat in the cells of the liver, which are called hepatocytes.

The liver processes all substances that are eaten, drunk, breathed in or absorbed through the skin. These substances are metabolized (broken down) into byproducts that the body can use or eliminate. The liver can function even after losing a large percentage of its cells to disease. Despite its resiliency, the liver can become damaged in many ways, including an increase in the levels of fat in the hepatocytes

Fatty liver is one end of a spectrum of conditions that can damage the liver. In some cases, fatty liver alone (steatosis) may be a mild condition. Some liver cells have extra fat but do not necessarily cause problems. However, recent studies link steatosis to complications including insulin resistance, which increases the risk of diabetes and heart disease. In addition, some cases of fatty liver progress to more serious conditions such as hepatitis and cirrhosis and can result in liver failure, but others do not. The mechanisms for progression are not well understood.

When fatty liver occurs with inflammation or liver cell damage, it is called steatohepatitis. This type can progress to cirrhosis, which is scarring of the liver resulting in severe tissue and cell damage. Cirrhotic tissue cannot be repaired and patients may eventually require liver transplantation.

There are two major forms of fatty liver: alcoholic and nonalcoholic. Each can cause fat to accumulate in the liver cells through different methods.

There are several possible reasons why fat accumulates in the liver cells, including:

• Fat is transferred from other parts of the body.
  
• The liver absorbs an increased amount of fat from the intestine.
  
• Fat accumulates more rapidly than the liver can metabolize it into a form that can be eliminated.

Eating a high-fat diet alone does not necessarily produce a fatty liver. There are other contributing factors, such as certain conditions and diseases, that cause fat to accumulate in the liver. The process by which these conditions lead to fatty liver is not completely understood.

Fatty liver occurs when fat makes up at least 10 percent of the liver. Fatty liver can occur in all age groups. Most patients are between the ages of 40 and 60. However, with rates of childhood obesity soaring, recent research indicates that millions of American children now have fatty liver.

In the United States and other Western countries, the most common causes of fatty liver include alcohol abuse, obesity and type 2 diabetes, a disorder in the body’s ability to use blood sugar. For people who consume alcohol in moderation, obesity and diabetes remain the most common causes. The incidence of both these conditions has increased dramatically in the United States over the past 20 years. However, fatty liver can occur in people of normal weight who do not have diabetes.

Several other conditions are potential causes of fatty liver. These include:

• Pregnancy.
  
  
• Use of certain medications, such as corticosteroids, a group of anti-inflammatory drugs used to reduce pain and ease conditions such as allergies, asthma and arthritis.
  
  
• Metabolic disorders, such as metabolic syndrome – a cluster of conditions that often occur together, including obesity, high blood sugar, high blood pressure and high triglycerides.
  
  
• Malnutrition or a low-protein diet.

In addition to the known and potential causes, certain risk factors for fatty liver have been identified. Risk factors increase a person’s likelihood of developing a given condition. However, some people develop the condition without any risk factors, and others may have multiple risk factors and never develop the condition. Risk factors for developing fatty liver include:

• Excessive alcohol consumption. People who consume large quantities of alcohol over a long period of time face a greater risk of damaging the liver.
  
  
• Weight. People who are overweight or obese are more likely to develop fatty liver.
  
  
• Diabetes.
  
  
• Hyperlipidemia. Elevated levels of cholesterol and triglycerides in the blood.
  
  
• Abdominal surgery. Surgery on the small intestine and, in some cases, stomach surgeries, such as gastric bypass for weight loss, increase the risk of fatty liver.
  
  
• Rapid weight loss. People who lose weight rapidly, either by dieting or after surgery, have an increased risk of fatty liver.
  
  
• Other liver diseases. Hepatitis B, hepatitis C and Wilson's disease are risk factors for fatty liver. People with the both forms of hepatitis already have inflammation in liver cells. Wilson’s disease is a rare genetic condition characterized by increased copper levels in the liver.
  
  
• Medications. In addition to corticosteroids, other medications that may contribute to fatty liver include synthetic estrogens (taken for menopause), the antiarrhythmia drug amiodarone, and tamoxifen, which is used to treat breast cancer.
  
  
• Total parenteral nutrition (TPN). People who receive all nutrients through an intravenous line and do not eat have a greater risk of developing fatty liver.
  
  
• Consumption of sugar. Recent research on animals suggests that eating sugar, particularly fructose, may increase the risk of fatty liver. High-fructose corn syrup, a common ingredient in processed foods, has been linked to health concerns including obesity and elevated levels of triglycerides.

A recent study of American children with nonalcoholic fatty liver disease suggests that additional risk factors, such as age, gender and ethnicity, may also play a role in the development of fatty liver. The condition was more common in older children, Hispanic children and boys.

Most patients with fatty liver usually do not have any symptoms. When symptoms occur, they may be generalized, such as fatigue or malaise (general sick feeling). They can also be centralized, such as abdominal tenderness on the right side or an enlarged liver.

In some cases, fatty liver is not discovered until it has progressed to a more serious condition, such as cirrhosis. Symptoms may include:

• Jaundice (yellowing of the skin and whites of the eyes)
• Nausea or vomiting
• Loss of appetite
• Unexplained weight loss
• Small, red spider veins under the skin
• Loss of interest in sex
• Fluid in the abdominal cavity (ascites)
• Itching on the hands and feet that progresses to other parts of the body
• Swelling (edema) in the legs or feet
• Mental confusion, such as forgetfulness or trouble concentrating (encephalopathy)

Because fatty liver often does not produce symptoms, many cases are identified during a routine physical examination or while investigating another condition or disease.

If fatty liver is suspected, a physician may gently press against the abdomen to determine whether the liver is larger than normal. A physician may also try to rule out other conditions that cause liver disease, such as hepatitis, and ask questions during a medical history about alcohol consumption and diet.

Fatty liver is a diagnosis of exclusion, meaning other conditions must be ruled out before it is considered. Blood tests are usually performed first, including liver function tests. These tests examine the levels of certain enzymes and proteins in the liver, in addition to the level of bilirubin, a chemical produced in the liver. Elevated enzyme or bilirubin levels may indicate fatty liver.

A liver biopsy is needed to confirm a diagnosis of fatty liver. A physician may order a biopsy if there is no history of alcohol abuse and the enzyme test levels are elevated. During this procedure, a needle is inserted into the abdomen and a tiny sample of liver tissue is removed. The tissue is examined under a microscope for the presence of excess fat in the liver. In addition to confirming the diagnosis, a liver biopsy can assess the level of liver damage and help indicate the prognosis.

Imaging tests may show some indicators of fatty liver, but they cannot distinguish between steatosis (without inflammation) and steatohepatitis (with inflammation and/or damage). Some imaging tests that may be used in addition to a liver biopsy include:

• Ultrasound. An imaging technology that uses sound waves to produce images of the shape and outline of various tissues and organs in the body. The images produced are called a sonogram. Ultrasound images are useful only when there is a lot of fat in the liver cells.
  
  
• CAT scan (computed axial tomography). A test that allows for multiple x-rays to be taken from different angles around the patient. It creates images of organs and bones within the body. It may be performed alone or with the use of a special dye (contrast medium).

• MRI (magnetic resonance imaging). A safe and noninvasive or minimally invasive imaging test that can help physicians diagnose diseases of numerous organs and vessels. It uses powerful magnets to produce images on a computer screen and film.

The treatment of fatty liver depends on its underlying cause. Some types of fatty liver, such as steatosis, may not require treatment. Many of the lifestyle adjustments that can treat fatty liver may also serve as methods to prevent the condition.

Treatments for fatty liver may include:

• Avoiding alcohol and other toxic substances. People may minimize damage or even reverse accumulation of fat by refraining from drinking alcohol or cutting down on the amount they drink. Patients can also avoid medications that may damage the liver, such as corticosteroids.
  
  
• Diet and exercise. Weight loss can reduce the amount of fat that accumulates in the liver. However, patients should not lose weight too quickly because it can worsen fatty liver. Regular exercise can also improve the condition.
  
  
• Diabetes control. Patients with diabetes should strictly manage the condition according to their physician’s treatment plan, which typically includes proper diet and exercise and may include medication. This may help to prevent further liver damage. Many of the diabetes patients who develop fatty liver do not manage their blood sugar levels well.
  
  
• Lowering cholesterol. Controlling high levels of cholesterol and triglycerides with diet, exercise and, in some cases, medication can help stabilize or possibly reverse fatty liver.

Several other treatments for fatty liver are being studied. However, it is unclear whether they are effective. They include:

• Vitamins E and C. Both vitamins are antioxidants, which are believed to reduce liver damage.
  
  
• Ursodiol. Medication used to treat gallstones, which reduces the production of bile acids. It is believed that they may reduce the level of liver enzymes in people with liver disease.
  
  
• Medications that counteract insulin resistance. Several medications are being tested in patients with nonalcoholic steatohepatitis (NASH). However, it is not clear whether patients benefit from the medications.
  
  
• Milk thistle. Herb used in Europe to treat liver disease. It is believed that it increases the production of antioxidant enzymes that help the liver break down toxins. It may also increase the production of new liver cells. Patients should not take milk thistle unless under the direction of a physician.
  
  
• Omega-3 fatty acids. Found in foods such as salmon and walnuts and in supplements, they may protect the liver.
  
  Researchers are also studying whether adding certain herbs and spices (e.g., cinnamon) to the diet can help reverse fatty liver.
  

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to fatty liver:

1. Why do you suspect fatty liver? What tests do you recommend to confirm this diagnosis?
   
   
2. If a liver biopsy is needed, how should I prepare? What can I expect during the procedure and what kind of recovery is involved? Are there any alternatives?
   
   
3. Do I need to limit or abstain from alcohol? Does the type of alcohol make a difference?
   
   
4. Is fatty liver dangerous to me? How often does it develop into cirrhosis of the liver?
   
   
5. Will I need periodic testing to ensure that my liver is not becoming inflamed and/or damaged? What type of tests and how often?
   
   
6. What diet and/or exercise changes do you recommend? Should I consult a dietician or exercise specialist? Can you recommend one?
   
   
7. Can my fatty liver be reversed? What steps can I take?
   
   
8. What is the best way to treat my case of fatty liver? Are there any over-the counter or prescription medication that may help?
   
   
9. What over-the-counter or prescription medications should I avoid to prevent worsening my fatty liver?
   
   
10. What symptoms or treatment side effects should I be immediately reporting to you?
    
    
11. Should members of my family be screened for this condition?