Non-Alcoholic Fatty Liver Disease

What Is Fatty Liver?

Fatty liver disease, also known as hepatic steatosis, is a condition characterised by the accumulation of fat in the liver cells.

In some cases, it could be due to excessive alcohol consumption, leading to alcoholic fatty liver disease. Non-alcoholic causes such as obesity, insulin resistance, high blood sugar, and certain medications can contribute to fatty liver disease.

Fatty liver disease can range from mild to severe and may progress to more serious conditions such as non-alcoholic steatohepatitis (NASH), liver fibrosis, cirrhosis, and liver cancer if left untreated.

What Is Non-Alcoholic Fatty Liver Disease (NAFLD)?

Non-Alcoholic Fatty Liver Disease (NAFLD) is a subtype of fatty liver disease that affects individuals who consume little to no alcohol. This condition often affects overweight or obese individuals and can lead to more severe liver diseases such as non-alcoholic steatohepatitis (NASH), which involves inflammation, liver cell damage, and liver cirrhosis. NAFLD is typically a silent disease with few or no symptoms, but it is closely linked to certain health conditions and diseases—including obesity.

4 Main Stages of Non-Alcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease (NAFLD) evolves through four main stages, each associated with specific changes in the liver's structure and function.

Simple Fatty Liver (Steatosis)

This stage represents the initial phase of NAFLD, marked by the accumulation of excess fat in liver cells. Typically, there is no inflammation or damage to the liver cells, and it often remains asymptomatic without complications.

Non-Alcoholic Steatohepatitis (NASH)

If NAFLD progresses, it can lead to non-alcoholic steatohepatitis (NASH), a more serious form of the disease. NASH is characterised by inflammation of the liver, which can damage the liver cells and potentially lead to scarring (fibrosis).

Liver Fibrosis

At this stage, ongoing inflammation causes scar tissue to form in the liver, replacing healthy liver tissue. This process of scarring is called fibrosis. While the liver can still function at this stage, its ability to regenerate and perform vital roles becomes increasingly impaired.

Liver Cirrhosis

This is the most severe stage of NAFLD. Cirrhosis occurs when the liver is extensively scarred, leading to a significant loss of liver function. It can result in serious complications, including liver failure and liver cancer.

Causes and Risk Factors for Fatty Liver Disease

Fatty liver disease can stem from various causes and risk factors. Excessive calorie consumption can lead to fat accumulation in the liver when it fails to process and break down fats properly. In some cases, fatty liver may also stem from alcohol abuse, rapid weight loss, and malnutrition.

Key risk factors for fatty liver include:


Being overweight or obese (with a body mass index of 25-30 or above 30, respectively)


Individuals with type 2 diabetes are more prone to fatty liver disease due to the association with insulin resistance, which can cause excessive fat buildup in the liver

High Blood Sugar

Persistently high blood sugar levels can contribute to fat accumulation in the liver

Elevated Levels of Fats in the Blood

Elevated levels of cholesterol and triglycerides can lead to the buildup of fat in the liver, resulting in fatty liver disease

High Blood Pressure

Hypertension has been associated with a higher risk of developing fatty liver disease

Autoimmune or Inherited Liver Diseases

Certain genetic disorders and autoimmune diseases can predispose individuals to fatty liver disease

Warning Signs of Non-Alcoholic Fatty Liver Disease

Non-Alcoholic Fatty Liver Disease (NAFLD) often presents no symptoms in its early stages. However, as the disease progresses, several warning signs may initially emerge:


Fatigue is a common symptom of many liver diseases, including NAFLD. Patients may feel constantly tired or weak.

High Blood Pressure

While high blood pressure is also a risk factor for NAFLD, it can also occur due to the disease. This is because NAFLD can contribute to the development of cardiovascular diseases.

Upper Abdominal Discomfort

Some people with NAFLD may experience discomfort or pain in the upper right of the abdomen, where the liver is located.

Symptoms of Advanced Non-Alcoholic Fatty Liver Disease

In the advanced stages of Non-Alcoholic Fatty Liver Disease (NAFLD), more severe symptoms may develop, such as:


Jaundice is characterised by a yellowing of the skin and eyes. This occurs when the damaged liver cannot properly process bilirubin, a by-product of red blood cell breakdown.

Abdominal Distension From Fluid Retention

Also known as ascites, this symptom arises when the liver cannot produce enough protein to hold fluid in the bloodstream, causing fluid to accumulate in the abdomen.

Internal Bleeding From Swollen Blood Vessels (Varices)

In response to liver damage, blood may flow into smaller vessels that cannot handle the increased volume. This can cause the vessels, particularly those in the oesophagus and stomach, to swell and potentially bleed.


Hepatic encephalopathy occurs when the liver cannot remove toxins from the blood, causing them to build up in the brain. This leads to confusion and other cognitive problems.


In severe cases of hepatic encephalopathy, the patient may fall into a coma due to the high levels of toxins in the brain.

Liver Failure

This is the most severe stage of liver disease. When the liver fails, it stops performing its essential functions, which can lead to a multitude of life-threatening complications.

When to See a Doctor for Non-Alcoholic Fatty Liver Disease

If you experience persistent fatigue, discomfort in the upper right abdomen, or any advanced symptoms like jaundice or abdominal distension, seek medical attention promptly.

Additionally, if you have risk factors such as obesity, diabetes, or high cholesterol, regular screenings can help detect NAFLD early.

Early intervention is key to managing NAFLD and preventing progression to more serious liver diseases.

How Is Non-Alcoholic Fatty Liver Disease (NAFLD) Diagnosed?

The diagnosis of NAFLD often involves a combination of blood tests, imaging procedures, and in some cases, a liver biopsy. These methods help determine the extent of liver damage and rule out other potential causes of liver disease.

Blood Tests

Blood tests can reveal liver function abnormalities and help identify other conditions that may cause similar symptoms. Elevated liver enzymes may suggest liver damage, particularly alanine aminotransferase (ALT) and aspartate aminotransferase (AST).

Imaging Procedures

Imaging tests such as ultrasound, CT scan, or MRI can show fat accumulation in the liver. These non-invasive procedures are often the first step in diagnosing NAFLD.

Liver Biopsy

A liver biopsy involves inserting a needle into the liver to collect a small tissue sample for examination under a microscope. A biopsy can confirm a diagnosis of NAFLD and show the degree of liver damage or inflammation.


This is a new method to diagnose NAFLD. It uses transient elastography, incorporating ultrasound, to quantify the fat content in the liver and measure liver stiffness, which has been proven to correlate with liver fibrosis or scarring. It is a quick, non-invasive, and painless test with higher accuracy. There is also no need for any anaesthetic, no risk of bleeding, and zero downtime.

Treatment Options for Non-Alcoholic Fatty Liver Disease (NAFLD)

Weight Loss

In overweight or obese individuals, losing weight can reduce fat in the liver. This may be achieved through a balanced diet and regular exercise.

Lifestyle/Dietary Modifications

Maintaining a healthy diet rich in fruits, vegetables, whole grains, and healthy fats helps manage NAFLD. It is also advisable to avoid high-calorie meals and saturated fat. Limiting alcohol consumption is also advised.

Bariatric Surgery to Achieve Weight Loss

In severe cases, bariatric surgery may be considered. In eligible patients, this can help achieve substantial weight loss and has been shown to improve liver health in people with NAFLD. However, it carries risks and should only be considered when other options have been exhausted and under careful medical supervision.

Frequently Asked Questions (FAQs)

What is the difference between Alcoholic Fatty Liver Disease (ALD) and Non-Alcoholic Fatty Liver Disease (NAFLD)?

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What happens if fatty liver remains undiagnosed and untreated?

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Can Non-Alcoholic Fatty Liver Disease (NAFLD) be reversed?

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Meet Our Specialist for Fatty Liver

Dr Kieron Lim

MBBS, University of LondonMember, Royal College of Physicians (UK)Fellow, Academy of Medicine (Gastroenterology) SingaporeFellow, Royal College of Physicians (Edinburgh)

With over two decades of specialist experience, Dr Kieron Lim is a Senior Consultant Gastroenterologist known for treating diverse gastrointestinal, liver, and pancreatic conditions. As the former Head of the Division of Gastroenterology and Hepatology at the National University Hospital, he is recognised for his patient outcomes and service quality. He also mentors medical professionals in complex hepatology cases and has contributed actively to the research and advancement of the field.