Nonalcoholic fatty liver disease (NAFLD) is an umbrella term for a range of liver conditions affecting people who drink little to no alcohol. As the name implies, the main characteristic of NAFLD is too much fat stored in liver cells.

NAFLD is increasingly common around the world, especially in Western nations. In the United States, it is the most common form of chronic liver disease, affecting about one-quarter of the population.

Some individuals with NAFLD can develop nonalcoholic steatohepatitis (NASH), an aggressive form of fatty liver disease, which is marked by liver inflammation and may progress to advanced scarring (cirrhosis) and liver failure. This damage is similar to the damage caused by heavy alcohol use.

NAFLD usually causes no signs and symptoms. When it does, they may include:

• Fatigue
• Pain or discomfort in the upper right abdomen

Possible signs and symptoms of NASH and advanced scarring (cirrhosis) include:

• Abdominal swelling (ascites)
• Enlarged blood vessels just beneath the skin's surface
• Enlarged spleen
• Red palms
• Yellowing of the skin and eyes (jaundice)

When to see a doctor

Make an appointment with your doctor if you have persistent signs and symptoms that cause you concern.

Experts don't know exactly why some people accumulate fat in the liver while others do not. Similarly, there is limited understanding of why some fatty livers develop inflammation that progresses to cirrhosis.

NAFLD and NASH are both linked to the following:

• Overweight or obesity
• Insulin resistance, in which your cells don't take up sugar in response to the hormone insulin
• High blood sugar (hyperglycemia), indicating prediabetes or type 2 diabetes
• High levels of fats, particularly triglycerides, in the blood

These combined health problems appear to promote the deposit of fat in the liver. For some people, this excess fat acts as a toxin to liver cells, causing liver inflammation and NASH, which may lead to a buildup of scar tissue in the liver.

A wide range of diseases and conditions can increase your risk of NAFLD, including:

• High cholesterol
• High levels of triglycerides in the blood
• Metabolic syndrome
• Obesity, particularly when fat is concentrated in the abdomen
• Polycystic ovary syndrome
• Sleep apnea
• Type 2 diabetes
• Underactive thyroid (hypothyroidism)
• Underactive pituitary gland (hypopituitarism)

NASH is more likely in these groups:

• Older people
• People with diabetes
• People with body fat concentrated in the abdomen

It is difficult to distinguish NAFLD from NASH without further testing.

The main complication of NAFLD and NASH is cirrhosis, which is late-stage scarring in the liver. Cirrhosis occurs in response to liver injury, such as the inflammation in NASH. As the liver tries to halt inflammation, it produces areas of scarring (fibrosis). With continued inflammation, fibrosis spreads to take up more and more liver tissue.

If the process isn't interrupted, cirrhosis can lead to:

• Fluid buildup in the abdomen (ascites)
• Swelling of veins in your esophagus (esophageal varices), which can rupture and bleed
• Confusion, drowsiness and slurred speech (hepatic encephalopathy)
• Liver cancer
• End-stage liver failure, which means the liver has stopped functioning

Between 5% and 12% of people with NASH will progress to cirrhosis.

To reduce your risk of NAFLD:

• Choose a healthy diet. Choose a healthy plant-based diet that's rich in fruits, vegetables, whole grains and healthy fats.
• Maintain a healthy weight. If you are overweight or obese, reduce the number of calories you eat each day and get more exercise. If you have a healthy weight, work to maintain it by choosing a healthy diet and exercising.
• Exercise. Exercise most days of the week. Get an OK from your doctor first if you haven't been exercising regularly.

Because NAFLD causes no symptoms in most cases, it frequently comes to medical attention when tests done for other reasons point to a liver problem. This can happen if your liver looks unusual on ultrasound or if you have an abnormal liver enzyme test.

Tests done to pinpoint the diagnosis and determine disease severity include:

Blood tests

• Complete blood count
• Liver enzyme and liver function tests
• Tests for chronic viral hepatitis (hepatitis A, hepatitis C and others)
• Celiac disease screening test
• Fasting blood sugar
• Hemoglobin A1C, which shows how stable your blood sugar is
• Lipid profile, which measures blood fats, such as cholesterol and triglycerides

Imaging procedures

Imaging procedures used to diagnose NAFLD include:

• Abdominal ultrasound, which is often the initial test when liver disease is suspected.
• Computerized tomography (CT) scanning or magnetic resonance imaging (MRI) of the abdomen. These techniques lack the ability to distinguish NASH from NAFLD, but still may be used.
• Transient elastography, an enhanced form of ultrasound that measures the stiffness of your liver. Liver stiffness indicates fibrosis or scarring.
• Magnetic resonance elastography, works by combining MRI imaging with sound waves to create a visual map (elastogram) showing the stiffness of body tissues.

Liver tissue examination

If other tests are inconclusive, your doctor may recommend a procedure to remove a sample of tissue from your liver (liver biopsy). The tissue sample is examined in a laboratory to look for signs of inflammation and scarring.

A liver biopsy can be uncomfortable, and it does have small risks that your doctor will review with you in detail. This procedure is performed by a needle insertion through the abdominal wall and into the liver.

The first line of treatment is usually weight loss through a combination of a healthy diet and exercise. Losing weight addresses the conditions that contribute to NAFLD. Ideally, a loss of 10% of body weight is desirable, but improvement in risk factors can become apparent if you lose even 3% to 5% of your starting weight. Weight-loss surgery is also an option for those who need to lose a great deal of weight.

For those who have cirrhosis due to NASH, liver transplantation may be an option.

Potential future treatments

No drug treatment has been approved by the Food and Drug Administration for nonalcoholic fatty liver disease, but a few drugs are being studied with promising results.

With your doctor's help, you can take steps to control your nonalcoholic fatty liver disease. You can:

• Lose weight. If you're overweight or obese, reduce the number of calories you eat each day and increase your physical activity in order to lose weight. Calorie reduction is the key to losing weight and managing this disease. If you have tried to lose weight in the past and have been unsuccessful, ask your doctor for help.
• Choose a healthy diet. Eat a healthy diet that's rich in fruits, vegetables and whole grains, and keep track of all calories you take in.
• Exercise and be more active. Aim for at least 30 minutes of exercise most days of the week. If you're trying to lose weight, you might find that more exercise is helpful. But if you don't already exercise regularly, get your doctor's OK first and start slowly.
• Control your diabetes. Follow your doctor's instructions to stay in control of your diabetes. Take your medications as directed and closely monitor your blood sugar.
• Lower your cholesterol. A healthy plant-based diet, exercise and medications can help keep your cholesterol and your triglycerides at healthy levels.
• Protect your liver. Avoid things that will put extra stress on your liver. For instance, don't drink alcohol. Follow the instructions on all medications and over-the-counter drugs. Check with your doctor before using any herbal remedies, as not all herbal products are safe.

No alternative medicine treatments are proved to cure nonalcoholic fatty liver disease. But researchers are studying whether some natural compounds could be helpful, such as:

• Vitamin E. In theory, vitamin E and other vitamins called antioxidants could help protect the liver by reducing or neutralizing the damage caused by inflammation. But more research is needed.

  Some evidence suggests vitamin E supplements may be helpful for people with liver damage caused by nonalcoholic fatty liver disease. But vitamin E has been linked with increased risk of death and, in men, an increased risk of prostate cancer.

• Coffee. In studies of people with nonalcoholic fatty liver disease, those who reported drinking two or more cups of coffee a day had less liver damage than those who drank little or no coffee. It's not yet clear how coffee may influence liver damage, but findings suggest it may contain certain compounds that may play a role in fighting inflammation.

  If you already drink coffee, these results may make you feel better about your morning cup of coffee. But if you don't already drink coffee, this probably isn't a good reason to start. Discuss the potential benefits of coffee with your doctor.

Start by making an appointment with your family doctor or primary doctor if you have signs and symptoms that worry you. If your doctor suspects you may have a liver problem, such as nonalcoholic fatty liver disease, you may be referred to a doctor who specializes in the liver (hepatologist).

Because appointments can be brief, it's a good idea to be well prepared. Here's some information to help you get ready, and what to expect from your doctor.

What you can do

• Be aware of any pre-appointment restrictions. When you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Make a list of all medications, vitamins or supplements that you're taking.
• Take any relevant medical records, such as records of any tests you've had that relate to your current condition.
• Take a family member or friend along. Sometimes it can be difficult to absorb all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
• Write down questions to ask your doctor.

If you find out you have nonalcoholic fatty liver disease, some basic questions to ask include:

• Is the fat in my liver hurting my health?
• Will my fatty liver disease progress to a more serious form?
• What are my treatment options?
• What can I do to keep my liver healthy?
• I have other health conditions. How can I best manage them together?
• Should I see a specialist? Will my insurance cover it?
• Are there any brochures or other printed material that I can take with me? What websites do you recommend?
• Should I plan for a follow-up visit?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

• Have you experienced any symptoms, such as yellowing of the eyes or skin and pain or swelling in your abdomen?
• If you had tests done at that time, what were the results?
• Do you drink alcohol?
• What medications do you take, including over-the-counter drugs and supplements?
• Have you ever been told that you have hepatitis?
• Do other people in your family have liver disease?