What is Non-Alcoholic Fatty Liver Disease (NAFLD) ?

"Non-alcoholic fatty liver" is both the name of a disease and a description of a variety of liver conditions ranging from fatty liver* to the more -serious non-alcoholic steatohepatitis (NASH), cirrhosis and liver failure.

A fatty liver has too much fat in its cells. When fat makes up at least 10 percent of the liver it is called a “fatty liver.” (See Figure 1.) Just as with the rest of the body, fat in the liver can cause it to become bigger.

This condition (and the range of conditions) are referred to as “non-alcoholic” to highlight the difference between NAFL and alcohol-related conditions. However, it is important to note that changes in the liver with non-alcoholic fatty liver are almost the same as those that result from drinking too much alcohol. NAFL requires attention to avoid additional, more-serious problems in the future.

If you have questions after reading this information, talk to your health care provider.

References to "fatty liver" refer to the condition of having fat in the liver. In this material, it does not refer to the range of liver conditions.

What is the liver and what does it do?

To understand alcohol-induced liver disease, it may help to know how a normal liver works.

At a weight of about 3 pounds, the liver is the largest solid organ in the body. (See Figure 1.) Everything you eat, drink, breathe, and absorb through your skin eventually reaches your liver. To be healthy, you need a healthy liver.

Good liver function is needed to:

• Make bile, which helps your body digest food and absorb nutrients
• Store sugar (glucose), your source for energy
• Help control your metabolism
• Make proteins, which help build muscles
• Clot blood
• Remove waste
• Break down toxic chemicals
• Filter medications to boost effectiveness

You may know that the liver has the ability to rebuild itself (regenerate its cells) if part of it becomes damaged. However, with NAFL, the progression of liver damage could go beyond the point when the liver is able to repair itself.

How is liver disease diagnosed?

As the name implies, this condition is related to being greatly overweight (obese). Up to 75 percent of men, women and children who are obese may have fatty liver and be at risk for NAFL.

The best way to learn whether you are overweight or obese is to use a guide called the body mass index (BMI). This guide considers your weight in relation to your height. If you are unsure whether you have a weight problem or want to learn if you would be considered "overweight" or "obese," talk to your health care provider.

BMI categories are:

• Normal weight: 19 to 24.9
• Overweight: 25 to 29.9
• Obese: 30 or greater

A person’s race (ethnicity) may help determine when their weight impacts the accumulation of fat in his or her liver. People of some nationalities tend to be diagnosed with fatty liver at a lower BMI than other people.

People who tend to deposit fat in the belly (abdomen) instead of the hips are more likely to have fatty liver. Your health care provider may measure your waist and hips to determine whether you have this tendency.

Excess weight in hips and thighs the belly (abdomen)

What are the causes of Fatty Liver & Non-alcoholic Steatohepatitis (NASH) ?

Eating fatty foods does not directly cause fatty liver. The specific causes of these conditions are unknown. However, it is believed that the events that lead to liver problems happen in a particular order:

• A person is overweight or obese.
• Extra weight leads to insulin resistance, when cells won’t let insulin transport sugar into the cells.
• The extra sugar stays in the blood, which leads to high blood sugar(hyperglycemia) and a high level of fat in the blood (hyperlipidemia). Other conditions may be caused too, such as high blood pressure (hypertension).
• These combined health problems lead to fatty deposits in the liver.
• For some people, fatty liver deposits cause liver inflammation (NASH).
• NASH eventually can lead to the build-up of scar tissue in the liver and other problems.

Other causes

Extra fat may come from other parts of the body and deposit in the liver, or the fat may be caused or affected by other conditions, including alcohol, other liver diseases and certain medications.

Progression to NASH and Cirrhosis

Although fatty liver itself is not always associated with inflammation or scarring of the liver, occasionally it may progress to more serious liver disease(s). If you have fatty liver and abuse alcohol or have other conditions that affect your liver, the damage to your liver could lead to a more serious condition.

The specific reason fatty liver progresses to NASH is unknown. Having too much fat in the liver may make the liver more vulnerable to inflammation and damage.

Non-alcoholic steatohepatitis (NASH)

Non-alcoholic steatohepatitis is a liver disease in which there is an accumulation of fat in the liver and inflammation of the liver cells. (Steato means fat and hepatitis means inflammation of the liver.) When the liver is inflamed, its cells are destroyed. Inflammation in the liver over time can lead to scarring (fibrosis). The only way to tell fatty liver and NASH apart is by a liver biopsy. (See page 6.)

Cirrhosis

In some people, NASH progresses to excessive scarring in the liver (cirrhosis). It isn’t known why some people are at high risk for this. Risk factors likely include diabetes and obesity.

Liver failure

Eventually the scarring can limit the ability of the liver to do its jobs and lead to liver-related symptoms. Continued damage to the liver could lead to liver failure. Both cirrhosis and liver failure (also known as “end-stage liver disease”) are life -threatening conditions. Immediate medical attention is needed. People with cirrhosis also are at increased risk of developing liver cancer.

What are the symptoms of NAFLD ?

Most people with fatty liver have no symptoms. Typical symptoms may include feeling tired (fatigued) and having abdominal discomfort on the right side. This is caused by pressure within the liver.

Cirrhosis offers no symptoms early on. As the disease progresses, the following symptoms may be diagnosed:

• Yellowing of the skin and eyes (jaundice)
• Collection of fluid in the belly (ascites)
• Bleeding in the esophagus, stomach or intestines (the gastrointestinal [GI] tract)
• Mental confusion (encephalopathy)

How is NAFLD Diagnosed ?

There is no one, specific test to diagnose fatty liver. The diagnosis is made by ruling out other causes of liver disease, such as excessive use of alcohol and viral hepatitis.

Fatty liver may be suspected in someone who has diabetes and/or is obese. Because most people have no symptoms with fatty liver, it may be found during routine tests. Tests that may be done to help diagnose fatty liver include:

• Blood tests to check liver enzymes — ALT (alanine aminotransferase) and AST

(aspartate aminotransferase) may be high in people with fatty liver.

• Ultrasound — This common imaging technique uses sound waves to “see” organs. An ultrasound is a painless way to look at the size, shape, texture, and blood supply of the liver.
• CT (computed tomography) and MRI (magnetic resonance imaging) scan — A

CT scan is a type of X-ray that takes cross-sectional pictures of the body and its organs. An MRI is a body scan that uses magnetic fields and radio waves (instead of X-rays) to piece together images of internal body parts. It shows a contrast between different types of soft tissue.

• Liver biopsy This minor surgical procedure uses ultrasound and a special needle to help take a small piece of tissue from the liver. The results may show fatty liver, inflammation caused by the fat in the liver, or scarring, as well as the amount or degree of each issue, if present. This is the only way to confirm diagnosis.

What is the treatment for NAFLD ?

Weight loss and physical activity are the only treatments for fatty liver. Medications for NASH are being studied, but none has been found to be effective. Talk to your health care provider about how to minimize some symptoms, if possible.

Your health care provider may suggest the following to help you feel better and possibly to help improve long-term survival:

• Maintain a healthy weight
• Manage diabetes and high triglycerides, if you have those conditions
• Increase physical activity
• Have medical evaluations on a schedule recommended by your health care provider
• Talk to your health care provider before taking any medications (prescribed or over the counter), vitamins and other supplements. Some of these can cause problems if you have liver disease.

Healthy weight

People with fatty liver who are overweight may benefit from a gradual weight loss. Weight loss and increased physical activity may result in reduced fat and inflammation in the liver and may prevent the condition from progressing to more serious liver disease.

A healthy diet consists of fresh fruits and vegetables; whole grains; lean meats, poultry and fish; and low-fat dairy products. Generally, it is best to follow an eating plan that is high in fiber and low in fat and sugar. Talk with your health care provider about your diet and whether you need to lose weight. You may want to consult a dietitian, as well.

Physical activity

People who are active tend to lose more weight and do better at keeping if off than people who are not active.

Exercise:

• May help reduce abdominal fat, a risk factor for fatty liver.
• May help control type 2 diabetes and hyperlipidemia.
• Does not have to be difficult to be a benefit. Walking is good exercise.

Check with your health care provider before starting an exercise program.

Remember

Non-alcoholic fatty liver disease is a condition that may improve with healthy lifestyle changes. NASH, cirrhosis and end-stage liver failure require medical care to help relieve the symptoms. It is important to have regular follow-up appointments with your health care provider to monitor these conditions.

For More Information

If you have questions after reading this information, talk to your health care provider.