Non-alcoholic fatty liver disease (NAFLD)
Your health expert: Dr Yiannis Kallis, Consultant Hepatologist and Gastroenterologist
Content editor review by Rachael Mayfield-Blake, May 2022
Next review due May 2025
Non-alcoholic fatty liver (NAFLD) is when fat builds up in the cells of your liver. It’s very common. Most people only have a mild form, which doesn’t usually cause long-term problems. But some people with NAFLD can go on to develop more serious liver damage. NAFLD isn’t caused by drinking too much alcohol.
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 the most common type of liver disease in developed countries. Around one in four people have the condition. Most people who develop NAFLD are between 40 and 65, but it’s becoming more 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.
Causes of non-alcoholic fatty liver disease
Non-alcoholic fatty liver disease (NAFLD) is caused by a build-up of fat in your liver. No one is certain why this happens. It may be 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 obese, 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 increase your risk
It’s thought that these two conditions might be increasing the number of people who are getting NAFLD. Other things that may increase your risk of getting NAFLD include:
Sometimes NAFLD can happen even if you don’t have any of the above.
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 you have a test for something else.
Sometimes, at a later stage, you may get non-alcoholic fatty liver disease 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
If NAFLD progresses further, you may get more symptoms, such as:
- itchy skin
- yellow skin and yellow in the whites of your eyes (jaundice)
- swollen legs, ankles, feet or tummy
- bruising
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 test for another health condition. This might include a blood test or an ultrasound scan of your tummy (abdomen).
If one of these tests shows there might be a problem with your liver, your GP will ask if you have any symptoms and examine you. They’ll 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. The GP may wish to do some other tests to check for other possible causes of liver problems.
If your GP suspects you have liver damage, they may refer you to a hepatologist (a doctor who specialises in conditions of the liver).
Blood tests (liver function tests)
Your doctor will give you a blood test and do a liver function test (LFT) to check whether your liver is inflamed or damaged and if it’s working properly. They’ll also check your blood cell count.
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 help diagnose NAFLD (see below).
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).
Other tests
You may have one or more of the following tests to help assess the extent of liver damage from NAFLD.
- Transient elastography (a fibroscan). In this test, a doctor or nurse will place a probe over your tummy (like an ultrasound) and move it over your liver. 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. Alternative options to assess the stiffness of your liver are an acoustic radiation force impulse imaging (ARFI) and an enhanced liver fibrosis (ELF) test.
- 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 can ask them questions about it.
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Self-help and diet for non-alcoholic fatty liver disease
The lifestyle changes below can help reduce your risk of getting NAFLD. Or, if you already have NAFLD, these changes can help to stop it from 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 1.0kg (1 to 2lb) per week.
- 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 manage to lose any weight.
- If you drink alcohol, it’s important to stay within the national recommended limits for alcohol consumption.
Non-alcoholic fatty liver disease diet
If you have NAFLD, aim to eat a healthy, balanced diet.
- Choose wholegrain carbohydrates (such as breads, rice and pasta) which are high in fibre.
- Don’t eat food and drinks that are high in sugar, and avoid salty/sugary snacks. Have healthier alternatives.
- Eat more vegetables and fruit.
- Eat less saturated fat. 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.
Treatment of non-alcoholic fatty liver disease
There isn’t any specific non-alcoholic fatty liver disease treatment yet. Your doctor will encourage you to make changes to your lifestyle to prevent your condition from getting worse (see our self-help and diet section above). Your doctor will also recommend treatment for any medical conditions or complications you may have because of NAFLD.
Medicines
There aren't any medicines to treat NAFLD yet. 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 may help to manage any problems associated with NAFLD. For example, your doctor may recommend medicines to treat high blood pressure, high cholesterol, and type 2 diabetes.
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 any changes you’ve made to your lifestyle have helped, and make sure your fatty liver doesn’t get any worse. Your GP will examine you and may do some tests, such as taking your blood pressure and measuring your body mass index (BMI). You might need to have some blood tests too.
Your GP or liver specialist may re-assess your risk of getting liver fibrosis at intervals too. They might suggest you have transient elastography (a fibroscan). See our diagnosis section above for more information on fibroscans.
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.
Surgery
If NAFLD progresses and you develop severe cirrhosis (see Stages of non-alcoholic fatty liver disease) your liver may stop working properly. You may need to be put on the waiting list for a liver transplant. Your surgeon will need to balance the risks of the operation with the benefits if you have other health conditions, such as obesity, or cardiovascular issues.
Complications of non-alcoholic fatty liver disease
There are several different stages of NAFLD, as described in our stages section above. Most people just have a fatty liver, and don’t have any long-term effects. But sometimes, the build-up of fat can cause 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 and are obese and/or have diabetes, you may be more at risk of developing cardiovascular disease, such as a heart attack or stroke. Your doctor will check if anything else puts you at risk, and help you to 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.
It depends on how severe your NAFLD is. Since alcohol is processed by your liver and if you have liver problems, it can be dangerous to drink. Even if you have liver disease that isn’t caused by alcohol, drinking can still make it worse. If your NAFLD is at the stage where your liver has started to show some inflammation, your doctor may advise you not to drink or to only drink small amounts of alcohol. If you have cirrhosis, it’s best not to drink at all.
See our section: Self-help and diet for non-alcoholic fatty liver disease above for more information.
This depends on what stage of NAFLD you have, and if you have any other health conditions. NAFLD can be more serious if you’re also overweight and have diabetes, for example, because this increases your risk of it getting worse. Ask your doctor to explain how serious your condition is.
See our section: Stages of non-alcoholic fatty liver disease above for more information.
All stages of NAFLD can affect your lifespan to some degree, but the more fibrosis you have, the more it’s going to affect you. Fibrosis is when damage to your liver is replaced by fibrous scar tissue. The most common cause of death in people with NAFLD is cardiovascular disease, but you can take steps to reduce your risk of this.
See our section: Self-help and diet for non-alcoholic fatty liver disease above for more information.
The liver is usually able to repair itself if any damage to it hasn’t gone too far. So, if you make some changes to your lifestyle and NAFLD is at an early stage, your liver may be able to repair itself. If you do plenty of exercise and lose any excess weight, you can reverse some of the build-up of fat and even some of the fibrosis in your liver, for example.
See our sections: Self-help and diet for non-alcoholic fatty liver disease and Treatment of non-alcoholic fatty liver disease above for more information.
It isn’t known exactly what causes a fatty liver if you don’t drink alcohol. It may be linked to the way your body responds to the hormone insulin, which is called insulin resistance. There are some things that may increase your risk of getting NAFLD, such as being overweight, especially if you carry extra weight around your middle.
See our section: Causes of non-alcoholic fatty liver disease above for more information.
There are different stages of NAFLD, ranging from a fatty liver (steatosis) where fat builds up in the cells of your liver but doesn’t cause any inflammation, to cirrhosis, which can lead to liver failure. The time it takes for NAFLD to progress will depend on your individual circumstances, such as whether you make changes to your lifestyle and how your liver responds to these. But if liver disease does progress to cirrhosis, it usually takes many years.
See our section: Stages of non-alcoholic fatty liver disease above for more information.
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