Definition

Nonalcoholic fatty liver disease (NAFLD) is the buildup of fat in the liver that is not caused by drinking too much alcohol. People who have it do not have a history of heavy drinking. NAFLD is usually but not always related to being overweight.

For many people, NAFLD causes no symptoms or problems. A more severe form of the disease is called non-alcoholic steatohepatitis (NASH). NASH can cause cirrhosis and liver failure. It can also cause liver cancer.

Alternative Names

Fatty liver disease; Steatotic liver disease; Nonalcoholic steatohepatitis; NASH; MASH; Metabolic dysfunction-associated steatohepatitis

Causes

NAFLD is the result of deposits of fat in the liver that are more than normal. Things that may put you at risk include any of the following:

• Being overweight or obese. The more overweight you are, the higher the risk.
• Prediabetes (insulin resistance).
• Type 2 diabetes.
• High cholesterol.
• High triglycerides.
• High blood pressure.

Other risk factors may include:

• Rapid weight loss and poor diet
• Gastric bypass surgery
• Bowel disease
• Certain medicines, such as calcium channel blockers and some cancer medicines
• Lack of exercise

NAFLD also occurs in people who have no known risk factors.

Symptoms

People with NAFLD often have no symptoms. When symptoms occur, the most common include:

• Fatigue
• Pain in the upper right abdomen

In people with NASH who have liver damage (cirrhosis), symptoms may include:

• Weakness
• Loss of appetite
• Nausea
• Yellow skin and eyes (jaundice)
• Itching
• Fluid buildup and swelling in the legs and abdomen
• Mental confusion
• GI bleeding

Exams and Tests

NAFLD is often found during routine blood tests that are used to see how well the liver is working.

You may have the following tests to measure liver function:

• Complete blood count
• Prothrombin time
• Blood albumin level
• Serum transaminases
• Blood tests that measure liver fibrosis

Your health care provider may order certain imaging tests, including:

• Ultrasound to confirm a diagnosis of NAFLD
• MRI and CT scan
• Fibroscan (elastography)

A liver biopsy is rarely needed to confirm a diagnosis of NASH, the more severe form of NAFLD.

Treatment

The treatment of NASH includes exercise, weight loss, lipid and glucose control. If you have evidence of scarring in the liver on the above testing, you may benefit from resmetirom (Rezdiffra), a recently approved drug to treat NASH. Resmetirom is a thyroid hormone receptor beta agonist, used in conjunction with diet and exercise, for the treatment of adults with noncirrhotic NASH with moderate to advanced liver fibrosis (consistent with stages F2 to F3 fibrosis).

Your provider will help you understand your condition and the healthy choices that can help you take care of your liver. These may include:

• Losing weight if you are overweight.
• Eating a healthy diet that is low in salt.
• Not drinking alcohol.
• Staying physically active.
• Managing health conditions such as diabetes and high blood pressure.
• Getting vaccinated for diseases such as hepatitis A and hepatitis B.
• Lowering your cholesterol and triglyceride levels.
• Taking medicines as directed. Talk to your provider about all medicines you take, including herbs and supplements and over-the-counter medicines.
• Treatment with with resmetirom, a recently approved drug for the treatment of NASH.

Losing weight and managing diabetes can slow or sometimes reverse the deposit of fat in the liver.

Outlook (Prognosis)

Many people with NAFLD have no health problems and do not go on to develop NASH. Losing weight and making healthy lifestyle choices can help prevent more serious problems.

It is unclear why some people develop NASH. NASH can lead to cirrhosis.

When to Contact a Medical Professional

Most people with NAFLD do not know they have it. See your provider if you begin to have unusual symptoms such as fatigue or abdominal pain.

Prevention

To help prevent NAFLD:

• Maintain a healthy weight.
• Eat a healthy diet.
• Exercise regularly.
• Limit alcohol consumption.
• Use medicines properly.

References

Chalasani NP, Maher J. Alcoholic and nonalcoholic steatohepatitis. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 138.

National Institute of Diabetes and Digestive and Kidney Diseases website. Eating, diet, and nutrition for NAFLD and NASH. www.niddk.nih.gov/health-information/liver-disease/nafld-nash/eating-diet-nutrition. Updated April 2021. Accessed May 23, 2025.

Rinella ME, Neuschwander-Tetri BA, Siddiqui MS, et al. AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease. Hepatology. 2023;77(5):1797-1835. PMID: 36727674 pubmed.ncbi.nlm.nih.gov/36727674/.

Torres DM, Harrison SA. Nonalcoholic fatty liver disease. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger and Fordtran's Gastrointestinal and Liver Disease. 11th ed. Philadelphia, PA: Elsevier; 2021:chap 87.