Non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the term for a range of conditions caused by a build-up of fat in the liver. You mostly see it in people who are overweight or obese.

A healthy liver should hold little or no fat. It's estimated that up to 1 in every 3 people has the early stages of NAFLD, where there are small amounts of fat in the liver.

Early-stage NAFLD doesn't usually cause any harm. But if it gets worse, it can lead to serious liver damage, including cirrhosis. High levels of fat in your liver are also linked with a higher risk of problems such as diabetes, heart attacks and strokes.

If NAFLD is found and managed early, it's possible to stop it getting worse and to reduce the amount of fat in your liver.

Non-alcoholic fatty liver disease (NAFLD) develops in 4 main stages.

Most people only ever reach the first stage, and they usually don't realise it. In a small number of cases the disease can progress and, if it isn't detected and managed, eventually lead to liver damage.

The main stages of NAFLD are:

• simple fatty liver (steatosis): a largely harmless build-up of fat in the liver cells, which may only be found during tests done for another reason
• non-alcoholic steatohepatitis (NASH): a more serious form of NAFLD, where the liver has become inflamed; this is estimated to affect up to 5% of the UK population
• fibrosis: persistent inflammation causes scar tissue around the liver and nearby blood vessels, but the liver can still work normally
• cirrhosis: the most severe stage, which comes after years of inflammation, when the liver shrinks and becomes scarred and lumpy; this damage is permanent and can lead to liver failure (where your liver stops working properly) and liver cancer

It can take years for fibrosis or cirrhosis to develop. It's important to make lifestyle changes to stop the disease from getting worse.

You're at a higher risk of non-alcoholic fatty liver disease (NAFLD) if you:

• are obese or overweight, particularly if you carry a lot of fat around your waist (an "apple-like" body shape)
• have type 2 diabetes
• have high blood pressure
• have high cholesterol
• are over the age of 50
• smoke

That said, NAFLD has been diagnosed in people with none of these risk factors, including young children.

NAFLD is very similar to alcohol-related liver disease (ARLD), but it isn't caused by drinking too much alcohol.

There usually aren't any symptoms of non-alcoholic fatty liver disease (NAFLD) in the early stages. You probably won't know you have it unless it's found during tests done for another reason.

Occasionally, people with NASH or fibrosis (more advanced stages of the disease) may have:

• a dull or aching pain in the top right of the tummy (over the lower right side of the ribs)
• fatigue (extreme tiredness)
• unexplained weight loss
• weakness

If cirrhosis (the most advanced stage) develops, the symptoms can be more severe. You can get yellowing of the skin and the whites of the eyes (jaundice), itchy skin, and swelling in the legs, ankles, feet or tummy.

Doctors often find non-alcoholic fatty liver disease (NAFLD) after a blood test called a liver function test comes back abnormal and other liver conditions, such as hepatitis, have been ruled out. But blood tests don't always pick up NAFLD.

It may also be spotted during an ultrasound scan of your tummy. This is a scan that uses sound waves to make an image of the inside of your body.

If you're diagnosed with NAFLD, you may need further tests to find out which stage you have. These may include a special blood test or another type of ultrasound scan (Fibroscan). Some people also need a biopsy, where a small sample of liver tissue is taken with a needle and analysed in a laboratory.

Most people with non-alcoholic fatty liver disease (NAFLD) won't develop any serious problems. Still, if you've been diagnosed with it, it's a good idea to take steps to stop it getting any worse.

There's currently no specific medicine for NAFLD, but healthy lifestyle choices can help. Treatment may also be recommended for conditions linked to it (high blood pressure, diabetes and cholesterol) or for any complications.

Your doctor may advise regular appointments to check how well your liver is working and to look for signs of any new problems.

Changing your lifestyle is the main way to manage non-alcoholic fatty liver disease (NAFLD). Each of the following can help.

Lose weight. You should aim for a BMI of 18.5 to 24.9. If you lose more than 10% of your weight, some fat can leave the liver, and NASH can improve if you have it.

Eat a healthy diet. Try for a balanced diet that is high in fruits, vegetables, protein and carbohydrates, but low in fat, sugar and salt. Smaller portions of food can help too.

Exercise regularly. Aim for at least 150 minutes a week of moderate-intensity activity, such as walking or cycling. All types of exercise can help improve NAFLD, even if you don't lose weight.

Stop smoking. If you smoke, stopping can help lower your risk of problems such as heart attacks and strokes.

Alcohol doesn't cause NAFLD, but drinking may make the condition worse. So it's advisable to cut down or stop drinking alcohol.

There isn't any medicine at the moment that can treat non-alcoholic fatty liver disease (NAFLD). But several medicines can help with the problems that come along with it.

Your doctor may recommend medicine to treat high blood pressure, high cholesterol, type 2 diabetes and/or obesity.

If you develop severe cirrhosis and your liver stops working properly, you may need to be put on the waiting list for a liver transplant.

For adults, the average waiting time for a liver transplant is 145 days when the liver comes from a recently deceased donor.

There's another option. It may be possible to have a transplant using a section of liver taken from a living donor. The liver can regenerate itself, so both the section given to you and the section left in the donor will regrow to a normal size.