Non-alcoholic fatty liver disease (NAFLD) is the term for a range of conditions caused by a build-up of fat in the liver. It's usually seen in people who are overweight or obese.
A healthy liver should contain little or no fat. It's estimated up to 1 in every 3 people in the UK has early stages of NAFLD, where there are small amounts of fat in their liver.
Early-stage NAFLD does not usually cause any harm, but it can lead to serious liver damage, including cirrhosis, if it gets worse.
If you already have diabetes, NAFLD increases your chance of developing heart problems.
If detected and managed at an early stage, it's possible to stop NAFLD getting worse and reduce the amount of fat in your liver.
NAFLD develops in 4 main stages.
Most people will only ever develop the first stage, usually without realising it.
In a small number of cases, it can progress and eventually lead to liver damage if not detected and managed.
The main stages of NAFLD are:
It can take years for fibrosis or cirrhosis to develop. It's important to make lifestyle changes to prevent the condition getting worse.
You're at an increased risk of NAFLD if you:
But NAFLD has been diagnosed in people without any of these risk factors, including young children.
Although it's very similar to alcohol-related liver disease (ARLD), NAFLD is not caused by drinking too much alcohol.
There are not usually any symptoms of NAFLD in the early stages. You probably will not know you have it unless it's diagnosed during tests carried out for another reason.
Occasionally, people with NASH or fibrosis (more advanced stages of NAFLD) may experience:
If cirrhosis (the most advanced stage) develops, you can get more severe symptoms, such as yellowing of the skin and the whites of the eyes (jaundice), itchy skin, and swelling in the legs, ankles, feet or tummy (oedema).
But blood tests do not always pick up NAFLD.
The condition may also be spotted during an ultrasound scan of your tummy.
This is a type of scan where sound waves are used to create an image of the inside of your body.
If you're diagnosed with NAFLD, further tests may be needed to determine which stage you have. This may involve a special blood test or having another type of ultrasound scan (Fibroscan).
Some people may also need a biopsy, where a small sample of liver tissue is taken using a needle so it can be analysed in a laboratory.
Children and young people with an increased risk of NAFLD (those with type 2 diabetes or metabolic syndrome) should have an ultrasound scan of their liver every 3 years.
Most people with NAFLD will not develop any serious problems, but if you're diagnosed with the condition it's a good idea to take steps to stop it getting any worse.
There's currently no specific medication for NAFLD, but making healthy lifestyle choices can help.
Treatment also may be recommended for associated conditions (high blood pressure, diabetes and cholesterol) or complications.
You may be advised to have regular appointments with your doctor to check your liver function and look for signs of any new problems.
There's not currently any medicine that can treat NAFLD, but various medicines can be useful in managing the problems associated with the condition.
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 135 days for transplants from recently deceased donors.
Or it may be possible to have a transplant using a section of liver removed from a living donor.
As the liver can regenerate itself, both the transplanted section and the remaining section of the donor's liver are able to regrow to a normal size.
Adopting a healthy lifestyle is the main way of managing NAFLD.
For example, it can help to:
NAFLD is not caused by alcohol, but drinking may make it worse. It's therefore advisable to cut down or stop drinking alcohol.