Fatty liver 101: Causes, Symptoms, Complications, and life expectancy.

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Definitions: What is fatty liver?

Nonalcoholic fatty liver diseases (NAFLD) is subdivided into the nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH)


  • NAFL (Nonalcoholic fatty liver): refers to the accumulation of the fat in the liver without inflammation.
  • NASH (nonalcoholic steatohepatitis): refers to the accumulation of fat inside the liver with subsequent liver inflammation.


Multiple factors interplay together to cause NAFLD. For example, food and dietary habits play a major role in NAFLD. However, NAFLD also has genetic and other risk factors contributing to its development.

Risk factors (reference):

  • Obesity.
  • Diabetes (type two).
  • Hypertension.
  • Dyslipidemia (increased lipids such as cholesterol and triglycerides).
  • Males are more likely to develop NASH than females.
  • Age also plays a role, the prevalence of NAFLD increases with age.
  • Race Hispanics have the highest prevalence of fatty liver (NAFLD), followed by Caucasians and African Americans.

How common is fatty liver disease?

NAFLD (nonalcoholic fatty liver disease) is the most common liver disease in western and industrialized countries (reference).

About 25% (one in every four persons) of the world population has NAFLD.

The prevalence of NASH (fatty liver with inflammation) is much lower. The prevalence of NASH worldwide is about 3 to 5% (one in every 20 persons).


NAFLD Prevalence

Africa 13.5%
Europe 23.7%
North America 24.1%
Asia 27.4%
South America 30.4%
Middle East 31.8%


  • Most commonly, people with fatty liver (NAFLD) are asymptomatic.
  • Vague symptoms such as fatigue and malaise.
  • Rarely, vague Right upper quadrant pain (liver pain).

Other findings:

  • Risk factors are often present (obesity, diabetes, hypertension, etc.).
  • Symptoms of complications (late stage): fatty liver can lead to fibrosis or cirrhosis of the liver. Symptoms of cirrhosis include jaundice, weight loss, abdominal distension (ascites), swelling of the lower limbs, and vomiting of blood.

How is fatty liver diagnosed?

The fatty liver (NAFLD) is diagnosed after excluding other chronic liver diseases such as chronic viral hepatitis, autoimmune hepatitis, and others.

The diagnosis is often based on abdominal imaging. However, we may need a biopsy if there is still a suspicion of an alternative diagnosis.

The list below illustrates the essential tools to diagnose fatty liver disease (NAFLD).



1. Abdominal Ultrasound Enlarged liver with fat accumulation (The liver is brighter than usual).
2. Liver Enzymes (ALT, AST) – Often abnormal, but in many cases, the enzymes are completely normal.
3. Transient elastography – Help define the grade (severity) of fat accumulation in the liver (steatosis).
4. Abdominal MRI (or CT) – Demonstrate the amount of fat.
5. Liver Biopsy – It is the gold standard for the diagnosis of fatty liver.
– Because it is an invasive maneuver, It is not widely used.
6. Tests to rule out similar liver diseases – Testing for hepatitis A, B, and C viruses.
– Plasma iron profile (to rule out hemochromatosis).
– Antibody tests to rule out immune-mediated liver diseases.

Complications and life expectancy of fatty liver disease.

NAFL (fatty liver without inflammation) can progress to NASH (fatty liver with inflammation.

NASH is less common than NAFLD; about 6-18% of people with NAFLD will have NASH (a more severe form) (reference).

When inflammation (NASH) develops, the liver cells become stressed. As a result, they are exposed to inflammation, death, and fibrosis.

You must know that these complications are relatively rare and take many years to evolve. It often affects people who don’t know they have fatty liver or are not compliant with diet and treatments.

The complications of NAFL and NASH include:

  • Liver Fibrosis: The liver becomes stiff and less capable of functioning at its maximum capacity.
  • Liver cirrhosis: When the destruction is massive, The liver cells regenerate in a disordered manner, and the liver function declines. Advanced cirrhosis cause jaundice, weight loss, ascites, lower limb edema, hepatic encephalopathy (coma), and bleeding varices (vomiting of blood.
  • Hepatocellular carcinoma: occurs as a complication of liver fibrosis or cirrhosis.
  • Death from cirrhosis or hepatocellular carcinoma.

One study found that each step of the above complications takes an average of 7.7 years to develop (reference).

Fatty liver life expectancy:

One study estimated that liver-related death in patients with NAFLD is less than one in every 1,000 people (0.77 per 1,000 person-years) (reference).

The most common cause of death in patients with NAFLD is not a liver disease. Instead, it is cardiovascular events (such as coronary artery disease) due to associated metabolic syndrome (hyperlipidemia, diabetes, and hypertension) (reference).

When probably managed and treated, the nonalcoholic fatty liver disease will not affect your life expectancy. One Danish study found that patients with NAFLD have a life expectancy similar to the general population (reference).

However, if left untreated, NAFLD can progress into fibrosis, cirrhosis, and hepatocellular carcinoma, significantly decreasing life expectancy.