Nonalcoholic fatty liver disease is associated with risk factors like obesity, high cholesterol, and type 2 diabetes. Recent research has also linked a fatty liver to hypothyroidism.

Excess fat in the liver may accumulate and lead to inflammation and scarring of the tissue. In severe cases, a fatty liver may lead to liver cancer and liver failure.

Hypothyroidism is one health condition that has more recently been linked to nonalcoholic fatty liver disease (NAFLD).

Hypothyroidism is the medical term for an underactive thyroid. The thyroid is a butterfly-shaped gland located on the front of the neck. It secretes hormones to help the body with growth, development, and metabolism.

With hypothyroidism, a person does not have enough thyroid hormone. They may not notice symptoms right away, but over time, they may develop heart issues, high cholesterol, or other health concerns.

A fatty liver is part of a condition called nonalcoholic fatty liver disease (NAFLD), also known as metabolic dysfunction-associated steatotic liver disease (MASLD). This disease is associated with certain health issues, including diabetes, kidney disease, and hypertension.

On its own, a fatty liver is not necessarily harmful. Your liver typically has some fat in it. However, excess fat, over 5% to 10% of your liver’s weight, in your liver may cause inflammation, scarring, liver cancer, or liver failure.

There are four stages of the progression of fatty liver.

Stages of fatty liver

Stage Effects on liver
1: steatosis (simple fatty liver)buildup of fat cells; not harmful
2: nonalcoholic steatohepatitis (NASH)inflammation
3: fibrosisscar tissue around the organ and blood vessels
4: cirrhosissevere damage and scarring; may lead to liver failure or liver cancer

Researchers have discovered that hypothyroidism may be a cause of fatty liver. This is a condition referred to as hypothyroidism-induced NAFLD.

People with hypothyroidism tend to have higher levels of total cholesterol and LDL cholesterol. They may also not move triglycerides out of the body as quickly as people without this condition.

As a result, hypothyroidism may cause NAFLD due to rising levels of LDL cholesterol combined with triglycerides in the liver tissue. When the fats accumulate in the liver, they cause oxidative stress and inflammation.

Leptin is another factor in this equation. Leptin tends to be elevated in people with hypothyroidism and NAFLD. This hormone may cause insulin resistance in the liver and lead to liver injury called hepatic fibrogenesis.

NAFLD may not have symptoms in the early stages. In fact, you may not experience symptoms for years. Some people may only discover they have a fatty liver through testing for other health issues.

If you do experience symptoms, they may include:

  • discomfort around the top right of the abdomen
  • confusion
  • fatigue
  • weakness
  • weight loss

Hypothyroidism also causes symptoms, such as fatigue, depression, pain and stiffness in the joints, and muscle weakness. You may notice these before you notice symptoms from NAFLD, or the symptoms may overlap.

The first step to diagnosis is making an appointment with a healthcare professional for a physical exam. At your appointment, your clinician will look for signs of insulin resistance, an enlarged liver, or clinical signs of cirrhosis. You will also discuss your symptoms and your health history.

Your healthcare professional may order the following tests:

There are no medications that can treat NAFLD caused by hypothyroidism specifically. Instead, the condition may be treated by managing the underlying hypothyroidism with levothyroxine (synthetic T4 hormone).

For many people, lifestyle changes may help relieve symptoms or reverse NAFLD. A healthcare professional may also recommend the following lifestyle changes as first-line treatment options:

  • limiting foods and drinks containing excess amounts of fructose
  • limiting alcohol consumption
  • engaging in regular physical activity

Oral drugs to treat hypothyroidism-induced NAFLD are in development as well, but they have yet to gain Food and Drug Administration (FDA) approval.

The outlook for people with fatty liver due to hypothyroidism can vary based on the stage of the disease and whether certain lifestyle changes and treatments are effective.

Research from 2018 suggests that NAFLD, due to its progressive nature, may lower a person’s life expectancy by around 4 years.

Over time, NAFLD may lead to more serious health issues like nonalcoholic steatohepatitis (NASH), cirrhosis, or hepatocellular carcinoma (HCC). Around 10% of people with NAFLD develop cirrhosis. When the liver is severely damaged, a liver transplant may help.

If you’ve received a NAFLD diagnosis, it’s important to speak with a healthcare professional about treatment and steps you can take to help lessen your symptoms and reduce any effects of the disease.

The liver filters toxins out of the bloodstream. Other important liver functions include helping with digestion (breaking down nutrients from food), blood sugar regulation, and protein synthesis.

According to a 2022 study, the prevalence of NAFLD in people with hypothyroidism is between 15.2% to 36.3%.

The liver can repair itself, provided there isn’t any permanent damage. Some experts recommend that people between 7% to 10% of their body weight to see improvement.

Before losing weight, or making any big lifestyle changes, it’s important to consult with a healthcare professional. They may be able to recommend treatments that are better suited to your specific needs.

Approximately 1 in 6 people with NAFLD also have some degree of hypothyroidism. You may not have symptoms of liver damage until the damage is severe.

Lifestyle changes can help and even reverse the effects on the liver in the early stages. Otherwise, work with your healthcare professional to find a treatment plan that takes your thyroid function into account.