The four stages of Non-Alcoholic Fatty Liver Disease (NAFLD)
Updated: Jul 27
Non-alcoholic Fatty Liver Disease (NAFLD) describes a range of conditions caused by too much fat stored in the liver in people who drink little or no alcohol. Healthy liver cells should contain little or no fat. More than 5% fat stored in liver cells is considered too much, and this can result in a fatty liver. 1 in 3 people in the UK is estimated to be affected by NAFLD.
There are four stages of Non-Alcoholic Fatty Liver Disease (NAFLD).
Simple fatty liver or steatosis
Non-alcoholic steatohepatitis (NASH)
The first stage is referred to as simple fatty liver or steatosis;
This occurs when the liver cells start to build-up fat, although there is no inflammation or scarring at this stage. There are often no symptoms in this early stage, so many people are unaware they have a fatty liver. For many people, fatty liver does not develop any further, and with a healthy diet and regular exercise, the excess fat in liver cells can be reduced. It is thought that approximately 20% of people with simple fatty liver, will go on to develop non-alcoholic steatohepatitis or NASH.
The second stage of NAFLD is non-alcoholic steatohepatitis (NASH);
This stage occurs when the build-up of fat in the liver cells is accompanied with inflammation. This stage is thought to affect up to 5% of the population in the UK, or 1 in every 20 people. Inflammation occurs when the liver is repairing damaged tissue. If the amount of damaged tissue increases, the liver may eventually struggle to repair it fast enough and the inflamed tissue can remain as a scar. When scar tissue starts to develop, this is known as fibrosis.
The third stage of NAFLD is fibrosis;
This occurs when there is persistent scar tissue in the liver and in the blood vessels around the liver. The liver can still function quite well at this stage, and removing or treating the cause of the inflammation may prevent further progression or even reverse some of the damage. However, if over time, the scar tissue starts to replace a lot of the normal liver tissue, the function of the liver is affected. This can lead to cirrhosis.
The fourth stage of NAFLD is cirrhosis;
At this stage, the liver stops working properly, and symptoms start to appear, such as yellowing of the skin and whites of the eyes and a dull ache in the lower right side of the ribs. The scar tissue in liver cirrhosis is difficult to remove, although further progression can be halted if the cause of the liver damage is removed.
Most people with NAFLD have the early stage of the disease (simple fatty liver or steatosis) and only a small number develop the more serious stages. It can take several years for fibrosis or cirrhosis to develop. Although there are often no symptoms accompanying the early stages of NAFLD, it is important to think about the health of your liver.
All stages of NAFLD are associated with an increased risk of developing cardiovascular diseases such as heart attack and stroke. Maintaining a healthy weight, limiting foods high in added sugars, eating a healthy, varied diet, not smoking and limiting or cutting out alcohol and exercising regularly will all help your liver function properly and keep you feeling healthy.