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Causes and Risk Factors for NASH

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By Editorial Team

3 min read

Reviewed by: HU Medical Review Board | Last reviewed: May 2024

There are many causes and risk factors of nonalcoholic steatohepatitis (NASH), which is an advanced form of nonalcoholic fatty liver disease (NAFLD). NAFLD and NASH do not happen by themselves. Often, they result from other health conditions that put extra strain on the liver, causing damage over time.1,2

Overview of NAFLD and NASH

NAFLD refers to a range of liver conditions in which fat builds up in the liver. NAFLD is often asymptomatic, meaning there are no obvious signs or symptoms. It can go unnoticed for years.1,2

In some cases, NAFLD progresses to NASH, which causes inflammation and liver damage. This damage can lead to other health problems like permanent scarring of the liver (cirrhosis), liver failure, and liver cancer.1

Causes of NASH

Experts are still working to understand why fat buildup occurs in some people’s livers and not in others. But they have identified several factors that contribute to the development of NASH.2-4

Overweight and obesity

Excess body weight, especially around the midsection, is strongly linked to NAFLD and NASH. Fat building up in the liver is more likely to occur in people with a higher body mass index (BMI).2-4

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High levels of cholesterol and triglycerides in the blood

Elevated levels of fats in the blood contribute to fat buildup in the liver. These fats include cholesterol (specifically LDL, the “bad” kind of cholesterol) and triglycerides.2-4

Insulin resistance

This occurs when the body’s cells become resistant to the effects of insulin, leading to higher blood sugar levels. Insulin resistance often occurs with obesity, type 2 diabetes, and metabolic syndrome. All of these conditions are common in people with NASH.2-4

Type 2 diabetes

Insulin resistance and high blood sugar levels, which occur with type 2 diabetes, greatly raise the risk of NASH.2-4

Genetics

Certain genetic changes (mutations) may make people more likely to develop NAFLD and NASH. These genetic factors can affect how the body processes fat, responds to insulin, and handles inflammation. Some rare genetic diseases such as Wilson disease can cause excess fat to build up in the liver.2-4

Risk factors for NASH

While anyone can develop NASH – both adults and children alike – several factors increase a person’s risk:2-4

  • Being over age 50
  • Having obesity, type 2 diabetes, and/or metabolic syndrome
  • Having cardiovascular disease like high cholesterol or high blood pressure
  • Having a family history of NAFLD or NASH
  • Eating a poor diet
  • History of a cholecystectomy (surgery to remove the gallbladder)
  • Living a sedentary lifestyle

Other health conditions that increase NASH risk

Several health conditions are linked to an increased risk of NASH, independent of their association with obesity. These include:2-5

  • Polycystic ovary syndrome (PCOS) – Research shows that women with PCOS, a hormonal disorder, more often have NAFLD because of insulin resistance and obesity.
  • Hypothyroidism – This term refers to an underactive thyroid gland, which may raise a person’s risk of NAFLD and NASH.
  • Obstructive sleep apnea – This is a disorder in which a person’s breathing repeatedly stops and starts during sleep because of blocked airways.
  • Rapid weight loss or malnutrition – This can put extra strain on the body, including the liver.

Prevention of NAFLD and NASH

While there is no guaranteed way to prevent NAFLD and NASH, there are many things you can do to reduce your risk of liver damage. Here are some actions you can take:2,4

  • Maintain a healthy weight.
  • Eat a balanced diet.
  • Exercise regularly.
  • Do not smoke.
  • Limit alcohol.
  • Manage other health conditions, including obesity, type 2 diabetes, high cholesterol, and high blood pressure.
  • Get regular health checkups.

When to see a doctor

Consult a healthcare provider if you have symptoms such as shortness of breath, swelling in the abdomen or legs, or yellowing of the eyes and skin (jaundice). People with risk factors for NASH, such as obesity, type 2 diabetes, or metabolic syndrome, should get regular medical checkups to monitor their overall health as well as their liver health.2

NASH is a serious liver condition that can lead to severe health complications if left untreated. Understanding the causes and risk factors can help you detect it early and manage the condition. If you suspect you have NAFLD or NASH or think you are at risk for liver disease, make an appointment with your doctor.1,2