What Is Non-Alcoholic Fatty Liver Disease?


Non-alcoholic fatty liver disease (NAFLD) is a manifestation of liver disease where fat builds up in the liver, occurring without excessive alcohol consumption. NAFLD is a common, often symptom-free condition that is closely linked with obesity and type 2 diabetes. 

NAFLD has a worldwide prevalence of about 25% with its continental incidence ranging from 13% in Africa to 32% in the Middle East.1 

When excess fat accumulates in the liver, it can cause inflammation and damage to liver cells. Most people with NAFLD are overweight or obese. NAFLD can range from a relatively harmless condition like a simple fatty liver (simple hepatic steatosis), found in 80% of people with NAFLD, to its most severe stage known as cirrhosis. The treatment ranges from lifestyle changes to liver transplants in very severe cases.

Causes of NAFLD

The exact cause of NAFLD is not known, however, some conditions make you more susceptible to developing NAFLD. The most common conditions linked to NAFLD are obesity, insulin resistance, type 2 diabetes, and high fat levels in the blood (dyslipidaemia). Other factors that may contribute to the development of NAFLD include genetic conditions associated with difficulties in breaking down fat, hepatitis C infection, medications like corticosteroids, tamoxifen, and amiodarone amongst others.

Signs and symptoms of non-alcoholic fatty liver disease

NAFLD usually presents with no symptoms in the early stages. Most people do not realise they have NAFLD until they do a blood test for other reasons. Some people with NAFLD may present with non-specific symptoms like tiredness, discomfort in the right upper part of the tummy, and weight loss. This is more common in the more advanced stages. They may also develop yellowness of the eyes and itching of the eyes and skin. Other symptoms, especially in advanced stages, may include swelling of the belly, blood in the vomit, black tarry stool, or even periods of confusion. 

Diagnosis of NAFLD

Most people with NAFLD go undiagnosed and some people only get diagnosed in advanced stages. NAFLD is often diagnosed after a liver function test and other causes of liver disease are ruled out. NAFLD is not always picked up in blood tests.

NAFLD may be identified via an ultrasound scan of the tummy. CT and MRI scans may also be useful in its diagnosis. Further tests may be required to determine the stage if NAFLD is diagnosed. This may include more blood tests and a special scan called fibroscan.

The definitive diagnosis of NAFLD is via a liver biopsy (tissue is taken from the liver and examined under the microscope).3

Management and treatment for non-alcoholic fatty liver disease

The main goals of treatment are to halt the progression of disease to prevent liver failure or cancer and to aid the liver in repairing itself and reversing NAFLD. 

Lifestyle modifications are the key component of treatment for NAFLD. These lifestyle modifications include weight loss, dietary modifications, reduction in alcohol intake, and exercise. Weight loss has been shown to reduce the amount of fat in the liver and could help in the regression of fibrosis (scarring).4

It is recommended that weight loss should be gradual, as rapid weight loss may worsen liver disease. The recommended goal of weight loss should be about 5-10% over 6 months. The European Association for Study of the Liver recommends a Mediterranean diet, which has the potential to reduce liver fat even when weight loss is not achieved. 

Exercise training should be moderate in intensity, aiming for 150 to 200 minutes per week over 3 to 5 sessions. Aerobic exercise training combined with dietary modifications has the most proven efficacy in managing NAFLD. 

Management of associated conditions like high blood pressure, diabetes, and high blood cholesterol is important in the management of NAFLD. There are no approved medications for the treatment of NAFLD, however, medications may be useful in treating associated conditions or managing complications.

Severe cases of NAFLD leading to liver failure or liver cancer may require a liver transplant.

Risk factors

There are several risk factors that increase the risk of NAFLD. These include smoking, obesity, high blood pressure, type 2 diabetes, and conditions that affect how your body uses insulin. Low physical activity and unhealthy diets have also been identified as risk factors for NAFLD. 


The complications of NAFLD can affect the liver, the cardiovascular system, and the metabolic system. NAFLD can lead to liver failure, sepsis, and liver cancer amongst others. It could also cause an increased risk of developing high blood pressure, chronic kidney disease, and type 2 diabetes. Cardiovascular disease is the leading cause of death in people with NAFLD. 


How common is non-alcoholic fatty liver disease?

About one in four people worldwide suffer from non-alcoholic fatty liver disease.1 It is one of the most common liver diseases in the United States and an estimated 24% of adults in the United States have NAFLD. 

How can I prevent non-alcoholic fatty liver disease?

Living a healthy life is important in the prevention of NAFLD. Maintaining a healthy weight, eating healthy, and adequate exercise are key. Managing chronic conditions like type 2 diabetes and high blood pressure, which increase the risk of NAFLD, is important in the prevention of NAFLD.

When should I see a doctor?

If you’re continually feeling tired or you have any right upper abdominal pain, see your doctor. If you experience any other symptoms of liver disease like yellowness of the eyes, itching, or change in the colour of your urine amongst others, please consult your doctor. You can also consult your doctor if you’re simply worried about developing NAFLD.


Non-alcoholic fatty liver disease (NAFLD) describes a variety of diseases that are caused by an accumulation of fat in the liver. There are conditions that increase your risk of developing NAFLD like obesity and type 2 diabetes. Most people do not have any symptoms and it usually goes undiagnosed. The management is mostly by lifestyle modification.


  1. Younossi ZM, Koenig AB, Abdelatif D, Fazel Y, Henry L, Wymer M. Global epidemiology of nonalcoholic fatty liver disease-Meta-analytic assessment of prevalence, incidence, and outcomes. Hepatology. 2016 Jul;64(1):73-84. doi: 10.1002/hep.28431. Epub 2016 Feb 22. PMID: 26707365. Available from: https://pubmed.ncbi.nlm.nih.gov/26707365/
  2. Kneeman, J. M., Misdraji, J., & Corey, K. E. (2012). Secondary causes of nonalcoholic fatty liver disease. Therapeutic advances in gastroenterology, 5(3), 199–207. Available from: https://doi.org/10.1177/1756283X11430859 
  3. Hashimoto E, Taniai M, Tokushige K. Characteristics and diagnosis of NAFLD/NASH. Journal of Gastroenterology and Hepatology [Internet]. 2013 Nov 19;28:64–70. Available from: https://doi.org/10.1111/jgh.12271
  4. Romero-Gómez M, Zelber-Sagi S, Trenell MI. Treatment of NAFLD with diet, physical activity and exercise. Journal of Hepatology [Internet]. 2017 Oct 1;67(4):829–46. Available from: https://doi.org/10.1016/j.jhep.2017.05.016
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Oluwadamilola Ogunsina

MBBS, MSc Public Health, London School of Hygiene & Tropical Medicine, England

Oluwadamilola is a medical doctor with several years of experience post-graduation. He is a higher psychiatry dual trainee in General Adult and Forensic Psychiatry. He loves education, mental health, preventive medicine and photography.

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