Overview

Nonalcoholic fatty liver disease (NAFLD) is an umbrella term for a range of liver conditions affecting people who drink little to no alcohol. As the name implies, the main characteristic of NAFLD is too much fat stored in liver cells.

NAFLD is increasingly common around the world, especially in Western nations. In the United States, it is the most common form of chronic liver disease, affecting about one-quarter of the population.

Some individuals with NAFLD can develop nonalcoholic steatohepatitis (NASH), an aggressive form of fatty liver disease, which is marked by liver inflammation and may progress to advanced scarring (cirrhosis) and liver failure. This damage is similar to the damage caused by heavy alcohol use.

Symptoms

NAFLD usually causes no signs and symptoms. When it does, they may include:

  • Fatigue
  • Pain or discomfort in the upper right abdomen

Possible signs and symptoms of NASH and advanced scarring (cirrhosis) include:

  • Abdominal swelling (ascites)
  • Enlarged blood vessels just beneath the skin's surface
  • Enlarged spleen
  • Red palms
  • Yellowing of the skin and eyes (jaundice)

When to see a doctor

Make an appointment with your doctor if you have persistent signs and symptoms that cause you concern.

Get the latest health information from Mayo Clinic delivered to your inbox.

Subscribe for free and receive your in-depth guide to digestive health, plus the latest on health innovations and news. You can unsubscribe at any time. Click here for an email preview.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

Causes

Experts don't know exactly why some people accumulate fat in the liver while others do not. Similarly, there is limited understanding of why some fatty livers develop inflammation that progresses to cirrhosis.

NAFLD and NASH are both linked to the following:

  • Overweight or obesity
  • Insulin resistance, in which your cells don't take up sugar in response to the hormone insulin
  • High blood sugar (hyperglycemia), indicating prediabetes or type 2 diabetes
  • High levels of fats, particularly triglycerides, in the blood

These combined health problems appear to promote the deposit of fat in the liver. For some people, this excess fat acts as a toxin to liver cells, causing liver inflammation and NASH, which may lead to a buildup of scar tissue in the liver.

Risk factors

A wide range of diseases and conditions can increase your risk of NAFLD, including:

  • High cholesterol
  • High levels of triglycerides in the blood
  • Metabolic syndrome
  • Obesity, particularly when fat is concentrated in the abdomen
  • Polycystic ovary syndrome
  • Sleep apnea
  • Type 2 diabetes
  • Underactive thyroid (hypothyroidism)
  • Underactive pituitary gland (hypopituitarism)

NASH is more likely in these groups:

  • Older people
  • People with diabetes
  • People with body fat concentrated in the abdomen

It is difficult to distinguish NAFLD from NASH without further testing.

Complications

The main complication of NAFLD and NASH is cirrhosis, which is late-stage scarring in the liver. Cirrhosis occurs in response to liver injury, such as the inflammation in NASH. As the liver tries to halt inflammation, it produces areas of scarring (fibrosis). With continued inflammation, fibrosis spreads to take up more and more liver tissue.

If the process isn't interrupted, cirrhosis can lead to:

  • Fluid buildup in the abdomen (ascites)
  • Swelling of veins in your esophagus (esophageal varices), which can rupture and bleed
  • Confusion, drowsiness and slurred speech (hepatic encephalopathy)
  • Liver cancer
  • End-stage liver failure, which means the liver has stopped functioning

Between 5% and 12% of people with NASH will progress to cirrhosis.

Prevention

To reduce your risk of NAFLD:

  • Choose a healthy diet. Choose a healthy plant-based diet that's rich in fruits, vegetables, whole grains and healthy fats.
  • Maintain a healthy weight. If you are overweight or obese, reduce the number of calories you eat each day and get more exercise. If you have a healthy weight, work to maintain it by choosing a healthy diet and exercising.
  • Exercise. Exercise most days of the week. Get an OK from your doctor first if you haven't been exercising regularly.

Nonalcoholic fatty liver disease care at Mayo Clinic

Sept. 22, 2021
  1. Pandyarajan V, et al. Screening for nonalcoholic fatty liver disease in the primary care clinic. Gastroenterology & Hepatology. 2019; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6676352/. Accessed Aug. 14, 2019.
  2. Non-alcoholic fatty liver disease. American Liver Foundation. https://liverfoundation.org/for-patients/about-the-liver/diseases-of-the-liver/non-alcoholic-fatty-liver-disease/. Accessed July 20, 2021.
  3. Nonalcoholic fatty liver disease (NAFLD) and NASH. National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/liver-disease/nafld-nash. Accessed July 20, 2021.
  4. Sheth SG, et al. Epidemiology, clinical features, and diagnosis of nonalcoholic fatty liver disease in adults. https://www.uptodate.com/contents/search. Accessed July 20, 2021.
  5. Kellerman RD, et al. Nonalcoholic fatty liver disease. In: Conn's Current Therapy 2019. Elsevier; 2019. https://www.clinicalkey.com. Accessed July 26, 2019.
  6. Wijarnpreecha K, et al. Coffee consumption and risk of nonalcoholic fatty liver disease: A systematic review and meta-analysis. European Journal of Gastroenterology and Hepatology. 2017. doi: 10.1097/MEG.0000000000000776.
  7. Ludwig J, et al. Nonalcoholic steatohepatitis: Mayo Clinic experiences with a hitherto unnamed disease. Mayo Clinic Proceedings. 1980;55:434.
  8. Nonalcoholic fatty liver disease (NAFLD). Merck Manual Professional Version. https://www.merckmanuals.com/professional/hepatic-and-biliary-disorders/approach-to-the-patient-with-liver-disease/nonalcoholic-fatty-liver-disease-nafld. Accessed July 20, 2021.
  9. Malhi H, et al. Nonalcoholic fatty liver: Optimizing pretransplant selection and posttransplant care to maximize survival. Current Opinion in Organ Transplantation. 2016. doi: 10.1097/MOT.0000000000000283.
  10. Heimbach JK, et al. Combined liver transplantation and gastric sleeve resection for patients with medically complicated obesity and end-stage liver disease. American Journal of Transplantation. 2013. doi: 10.1111/j.1600-6143.2012.04318.x.
  11. Bazerbachi F, et al. Recent clinical results of endoscopic bariatric therapies as an obesity intervention. Clinical Endoscopy. 2017. doi: 10.5946/ce.2017.013.
  12. Jensen NA. Allscripts EPSi. Mayo Clinic. July 2, 2021.

Related

Associated Procedures

News from Mayo Clinic

Products & Services