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Non-alcoholic fatty liver disease (NAFLD)


Expert reviewer, Dr Yiannis Kallis, Consultant Hepatologist and Gastroenterologist
Next review due February 2023

Non-alcoholic fatty liver (NAFLD) is a condition where fat builds up in the cells of your liver. It’s very common, but most people only have a mild form, which doesn’t usually cause long-term problems. However, some people with NAFLD can go on to develop more serious liver damage.

Unlike alcohol-related liver disease, NAFLD isn’t caused by drinking too much alcohol.


An image showing a diagram of the liver and surrounding structures

About non-alcoholic fatty liver disease

If your liver is healthy, there should be little or no fat in it. But sometimes, for a variety of reasons, fat can begin to collect in your liver cells. This can sometimes be due to drinking too much alcohol. But if the build-up of fat isn’t linked to alcohol, it’s called non-alcoholic fatty liver disease (NAFLD). NAFLD is more common if you’re overweight or have diabetes. For more information on this, see our Causes section below.

If you have NAFLD, making changes to your lifestyle, including improving your diet and exercising more, may help to prevent or reverse damage to your liver. See our self-help and diet section below for tips and advice.

NAFLD is the most common type of liver disease in developed countries. It’s thought that more than one in five people have the early stage of the condition. Most people who develop NAFLD are between 40 and 60, but it’s becoming increasingly common in children and teenagers.

Stages of non-alcoholic fatty liver disease

There are different stages or levels of NAFLD.

  • Fatty liver (steatosis). This is when fat builds up in the cells of your liver but doesn’t cause any inflammation. Most people with NAFLD will only have this stage.
  • Non-alcoholic steatohepatitis (NASH). This is when the build-up of fat causes your liver to become inflamed and damaged.
  • Fibrosis. This is when damage to your liver is replaced by fibrous scar tissue. In the early stages, this might be reversible to some extent.
  • Cirrhosis. This is when the long-term scarring to your liver becomes severe and irreversible. Your liver becomes harder and its smooth tissue is replaced by hard irregular nodules. Cirrhosis can lead to liver failure.

Symptoms of non-alcoholic fatty liver disease

NAFLD doesn’t usually cause any symptoms in the early stages. You may only find out you have it if it’s found in a test you’re having for something else.

Sometimes, if your liver gets to the stage where it’s damaged, you may get symptoms which can include:

  • feeling generally unwell and really tired
  • pain or discomfort on the right side of your tummy (abdomen), just under your ribs
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Diagnosis of non-alcoholic fatty liver disease

You might only find out that you’ve got a problem with your liver when you have a routine medical test or a test for another health condition. This might include a blood test or an ultrasound scan of your abdomen (tummy).

If one of these test shows there might be a problem with your liver, your GP will ask if you have any symptoms and examine you. They’ll also ask you about your medical history and your lifestyle, and may weigh you to check your body mass index (BMI). It’s important to be honest about your lifestyle, and about how much and how often you drink alcohol. This will help your GP to make the right diagnosis of the type of fatty liver disease you may have.

If your GP suspects you have liver damage, they may refer you to a hepatologist (a doctor who specialises in conditions of the liver).

You’ll be offered a blood test to check how well your liver is working and to check your blood cell count. For more information on this, see our FAQ on liver function tests below. But blood tests alone aren’t always reliable because some people have liver damage despite having normal blood tests. So, your doctor may recommend an ultrasound scan of your abdomen to see if there’s any fat in your liver.

Your GP may use the results of blood tests, together with information such as your age and BMI, to assess your risk of liver fibrosis (scarring).

You may also need to have one or more of the following tests.

  • Transient elastography (a fibroscan). This is non-invasive test, rather like having an ultrasound scan. A fibroscan measures the stiffness of your liver to see how much fibrosis (scarring) it has. Some fibroscans can also see how much fat there is in your liver.
  • A liver biopsy. In this test, your doctor will insert a very fine hollow needle into your liver to collect a small sample of tissue. This is done under local anaesthesia and the sample will be sent to a laboratory to be tested.

If your doctor recommends you have a test, they’ll explain what’s involved and you’ll have the chance to ask any questions.

Treatment of non-alcoholic fatty liver disease

There aren’t any specific treatments yet for NAFLD. Your doctor will encourage you to make changes to your lifestyle to prevent your condition getting worse. For more information about these, see our self-help and diet section below. Your doctor will also recommend treatment for any medical conditions or complications you may have because of your NAFLD.

Medicines

There aren't any medicines to treat NAFLD yet. However, there’s lots of research going on to try to find a treatment, especially for people with the more advanced stages of liver fibrosis and inflammation. There are various medicines that are useful in managing problems associated with NAFLD. For example, your doctor may recommend medicines to treat high blood pressure, high cholesterol, and type 2 diabetes if you have these conditions.

Monitoring

If you have NAFLD, your GP will monitor your condition from time to time (probably at least every year). They might refer you to see a specialist for further assessment. This can show if making changes to your lifestyle is working, and help to make sure your liver doesn’t get any worse. Your GP will examine you and may do some tests, such as take your blood pressure and measure your body mass index (BMI). You might need to have some blood tests too.

Every three years, your GP may re-assess your risk of getting liver fibrosis. They might suggest you have transient elastography (a fibroscan). See our section on diagnosis above for more information on this.

If you stick with the changes you make to your lifestyle, your liver may improve. If you don’t make any changes, your fatty liver may progress into more serious liver disease and damage.

Self-help and diet for non-alcoholic fatty liver disease

If you have NAFLD, you can make lifestyle changes to help stop it getting worse.

  • Lose any excess weight. This can reverse some of the build-up of fat and even some of the fibrosis in your liver. It’s important not to lose weight too quickly though, because this could cause problems with your liver. Aim for 0.5 to 1.0 kg (1 to 2 lbs) per week. For more about what to eat, see our information on diet and fatty liver below.
  • Exercise more. This will help you to lose any excess weight you may have. It may also help to reduce damage to your liver even if you don’t successfully lose any weight.
  • If you drink alcohol, it’s important to stay within the national recommended limits for alcohol consumption. For more information, see our FAQ: Alcohol and non-alcoholic fatty liver disease below.

Non-alcoholic fatty liver disease diet

If you have NAFLD, you should aim to eat a healthy, balanced diet.

  • Choose wholegrain carbohydrates (such as breads, rice and pasta) which are high in fibre.
  • Avoid food and drinks that are high in sugar.
  • Eat more vegetables and fruit.
  • Eat less saturated fat. Replace saturated fats with monounsaturated fats or polyunsaturated fats, especially omega-3 fatty acids. This may help reduce your risk of heart disease which can be linked to NAFLD.
  • Monitor your portion sizes, especially if you’re trying to lose weight.

For more advice on making healthy lifestyle changes, see our ‘Related information’ section below.

Causes of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease is caused by a build-up of fat in your liver. No one is certain why this happens. Many doctors believe that it’s linked to the way your body responds to the hormone insulin – this is called insulin resistance.

You may be more at risk of getting NAFLD if:

  • you’re overweight, especially if you carry extra weight around your middle
  • you have type 2 diabetes
  • you have high blood pressure (hypertension)
  • you have high levels of fats in your blood stream – known as hyperlipidaemia
  • other people in your family have NAFLD or have these conditions which makes a person more at risk

Complications of non-alcoholic fatty liver disease

There are several different stages of NAFLD, as described in our section on stages above. Most people just have a fatty liver, and don’t have any long-term effects. But for some people, the build-up of fat causes inflammation and scarring, which can lead to the complication of serious liver disease. This can also increase your risk of getting liver cancer.

If you have NAFLD, especially if you also have type 2 diabetes, you’re more at risk of developing cardiovascular disease, such as a heart attack or stroke. Your doctor will check if anything else is also putting you at risk, and help you take steps to reduce it. For example, they’ll check your blood pressure and cholesterol levels to see if these are within the normal range. You might need to take medicines to control these.

Preventing non-alcoholic fatty liver disease

You can reduce your risk of getting NAFLD by:

  • maintaining a healthy weight through eating a healthy, balanced diet
  • being active and getting plenty of exercise

For tips and hints on living a healthy lifestyle, see our ‘Self-help and diet’ section above and the related information section below.

Frequently asked questions

  • It’s difficult for doctors to be precise about how much is safe for you to drink if you have NAFLD, but it’s clear that you shouldn’t drink to excess. Aim to stay within the national recommended alcohol limits of not more than 14 units a week (for both men and women). These should be spread evenly, not saved up for a few days. It’s a good idea to have several alcohol-free days to give you and your liver a break from drinking.

    Alcohol is processed by your liver. This means that if you have liver problems, it can be dangerous to drink. Even if you have liver disease that isn’t caused by drinking too much alcohol, drinking can still make it worse. If your NAFLD is at the stage where your liver has started to show some inflammation, you may be advised to drink only modest amounts of alcohol. If you have cirrhosis, you shouldn’t drink any alcohol at all.

    If you have NAFLD, talk to your doctor about how much alcohol is safe for you to drink.

  • Liver function tests (LFTs) can help show whether your liver is inflamed or damaged, and if it’s working properly. The tests involve taking a sample of your blood and carrying out different tests on it in a laboratory.

    Getting an abnormal liver function test result doesn’t necessarily mean that you have a serious liver problem. Some of the tests aren’t very specific and an abnormal test can be caused by other conditions.

    If you have NAFLD, your liver function test results may be abnormal. But a normal result doesn’t rule out liver problems. That’s why your doctor may recommend other tests such as an ultrasound scan to check for NAFLD.


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Related information

Tools and calculators

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    • Personal communication, Dr Yiannis Kallis, Consultant Hepatologist and Gastroenterologist, February 2020
  • Reviewed by Dr Kristina Routh, Freelance Health Editor, Bupa Health Content Team, February 2020
    Expert reviewer, Dr Yiannis Kallis, Consultant Hepatologist and Gastroenterologist
    Next review due February 2023



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