An Overview of Fatty Liver Disease: Part 1 of Liver Health

In the human body, each organ that we have has a role to play to keep us balanced and healthy. One of the organs we have is the liver, and its functions range from filtering out harmful toxins to making compounds that breakdown the food we eat. Without the liver, we cannot survive. 

Like other organs in the body, the liver can become diseased and not work properly. The most common type of liver disease is called fatty liver disease, which results from excess amounts of fat being stored in the liver. And while fatty liver disease is typically treatable and reversible, it can sometimes progress to conditions that cause permanent scarring, damage, and even cancer of the liver. 

For this reason, it’s important to me that patients understand what fatty liver disease is, what causes it, how it’s diagnosed, and how to treat it while it’s still reversible. But in order to understand what fatty liver disease is, we first need to understand what the liver does for our bodies.

What Does the Liver Do?

Many people know of the liver's function of filtering out toxins in our body, but it does much more than that.

In addition to breaking down and filtering out toxins in our body, the liver also:

  • Breaks down and uses carbohydrates and fats for energy

  • Stores glucose in our muscle cells for back up energy

  • Stores vitamins

  • Creates bile, which we need to break down fats in the food we eat and also get rid of waste in the body

  • Creates albumin, which is a blood protein that helps our body keep fluid and blood in our blood vessels 

  • Recycles old blood cells - a process that produces a substance called bilirubin, which is a part of bile

  • Breaks down hormones like insulin and estrogen

  • Breaks down medications

Because the liver does so much in the body, it’s so important to be aware of certain diseases that can affect the liver. And one of the main diseases is called fatty liver disease.

What Is Fatty Liver Disease?

Fatty liver disease, which is medically referred to as Steatotic Liver Disease, is an umbrella term that covers all fatty liver disease states. Fatty liver disease is what’s defined as fatty deposits in the liver, and the majority of cases happen as a result of something called metabolic syndrome. Other causes of fatty liver disease include consuming a lot of alcohol or being exposed to certain environmental toxins.

Metabolic syndrome is a group of five conditions that has been found to increase the risk of diabetes, heart attack, and stroke. The five conditions that make up metabolic syndrome include:¹

  • Obesity

  • High blood sugar levels

  • High blood pressure

  • High triglyceride levels

  • Low HDL levels

Fatty liver disease was originally divided into two categories: non-alcoholic and alcoholic. But we now know that liver disease is not just caused by alcohol ingestion, but that it is also caused by many metabolic and environmental factors. So including the phrase “non-alcoholic” was confusing for patients and providers.

It’s known by several different names including:

  • Non-Alcoholic Fatty Liver Disease (NAFLD)

  • Metabolic Associated Fatty Liver Disease (MAFLD)

  • Metabolic Dysfunction Associated Steatotic Liver Disease (MASLD)

Because of what we now know about fatty liver disease, the name of NAFLD changed to MAFLD in 2019. The name just changed again to MASLD in 2023 to give further credit to the metabolic dysfunction that causes fatty liver disease. So while it’s known under many names, I’ll be using the most recent name of MASLD. 

How Common Is Fatty Liver Disease?

It’s estimated that 38% of people worldwide have MASLD, and this number is projected to increase in the coming years. By 2040, it’s estimated that MASLD will affect 55.4% of people in the world.²

And MASLD doesn’t just affect adults; it affects children too. 

MASLD is the leading cause of chronic liver disease in children worldwide, and it affects 7.6% of children in general and 34.2% of children with obesity.³ In America, 5-10% of children have MASLD.⁴

Liver disease in children used to not be as common, but we’ve recently seen a large increase in liver disease among children, especially in westernized nations.² Since 2017, we’ve seen a 168.3% increase in MASLD in children.⁵

And in those people with MASLD, they are at an increased risk of developing conditions that can cause permanent and life-threatening damage to the liver.

Why Do We Need to Worry About Fatty Liver Disease? 

Fatty deposits in the liver may not seem too harmful to the body, but every fatty deposit in the liver is taking the place of healthy liver cells. And over time, these fatty deposits can cause inflammation and dysfunction of the liver. These inflammatory changes happen in about 20% of people with MASLD, and the resulting condition is called Metabolic Dysfunction-Associated Steatohepatitis (MASH).⁶ Until recently, this was called Non-Alcoholic Steatohepatitis (NASH).

In people that develop MASH, about 11% of people can develop cirrhosis of the liver.⁶ This happens because there is so much inflammation in the liver from MASH that scar tissue forms. This scar tissue in the liver is also called fibrosis. People that develop cirrhosis have a much worse prognosis, and once the scar tissue starts to develop, it’s much harder to recover from. 

Additionally, having cirrhosis of the liver causes liver cancer in about 7% of people. In medical terms, it’s known as hepatocellular carcinoma (HCC). In those that don’t develop cancer from cirrhosis, about 31% of people will suffer from liver failure. 

MASH is the fastest rising cause of liver cancer in the world, and it’s the fastest rising reason for liver transplants in America, including both adults and children.²

The timeline of fatty liver disease to cirrhosis, liver failure, and liver cancer.⁶

What Are the Causes of Fatty Liver Disease?

Fatty liver disease is a complex illness that can vary in severity from person to person. However, there are certain things that can increase the risk of developing MASLD, which include:

  • Increased age

  • Male gender

  • Hispanic and caucasian race

  • Tobacco use

  • Obesity

  • Sedentary work and lifestyle

  • High caloric intake

There are also some genetic risk factors that have been linked to developing MASLD, but it’s important to remember that genetics just give us a probability. They don’t necessarily tell us the whole story. Our environment plays a huge role in what genes our bodies express.

The causes of fatty liver disease vary, but the top three things that contribute to fatty liver disease are metabolic syndrome, alcohol, and environmental toxins. Each one of these causes share one thing in common, and it’s that they’re putting strain and increased pressure on the liver to detox. 

If someone is overweight and eats extra food, the liver gets overwhelmed and runs out of room to store these extra calories in the body. So it responds by storing them in the liver in the form of fatty deposits. 

Similarly, when we’re exposed to a lot of toxins, our livers get overloaded with the amount of toxins it has to process. It responds to this by storing these toxins as fatty tissue in the liver. The frequency of fatty liver disease has increased so much because more and more of these harmful toxins and chemicals are being found in our food and environment. 

What Are The Symptoms of Fatty Liver Disease?

Because of how serious fatty liver disease is, it’s important to be aware of the symptoms of it. However, the tough thing about fatty liver disease is that it doesn’t typically start to cause symptoms until it has progressed to MASH. 

But some people do have early symptoms of fatty liver disease, and these symptoms include:

  • Dull, aching pain over the liver, which is located in the top right part of the abdomen

  • Fatigue

  • Weight loss

  • Weakness

If fatty liver disease has progressed to MASH, you may have symptoms like:

  • Yellowing of the skin and eyes, which is called jaundice

  • Bloating of the abdomen due to fluid build-up, which is called ascites

  • Increased frequency of illness due to poor immune function

Because symptoms don’t usually occur until fatty liver disease has reached a stage that is no longer reversible, early detection and diagnosis is key!

How is Fatty Liver Disease Diagnosed?

Liver disease is diagnosed and evaluated with different testing including blood work, imaging, and biopsies. If liver enzymes like AST, ALT, and alkaline phosphatase are noted to be elevated on blood work, imaging of the liver and sometimes a liver biopsy is used to confirm the diagnosis. 

Blood Work Used To Diagnose Fatty Liver Disease

Because MASLD doesn’t typically cause symptoms, it’s often incidentally diagnosed on routine blood work. The main blood tests that I use to screen for fatty liver disease in all of my patients include:

  • Aspartate aminotransferase (AST)

  • Alanine transaminase (ALT)

  • Alkaline Phosphatase

  • Gamma-glutamyltransferase (GGT)

  • Fasting Insulin

  • Hemoglobin A1c

  • Vitamin D

  • Iron

  • Ferritin

  • Cholesterol

  • Triglycerides

  • Cardiac-reactive protein (CRP)

  • Homocysteine

  • Growth hormone

  • Sex hormones

  • Thyroid hormones

Additionally, there are tests like the Fibrotest and the Steatotest that assess scarring, inflammation, and the extent of fatty deposits in the liver. 

Many primary care providers will order basic labs that check liver enzymes, but one of the most important blood tests that I check on my patients is GGT. I make sure to check this on all of my patients because it allows me to know if patients are at an increased risk of having fatty liver disease that progresses to permanent scarring. Additionally, elevated GGT levels have been shown to be linked to other diseases like:⁷

  • Heart disease

  • Heart failure

  • High blood pressure

  • Diabetes

  • Viral Hepatitis 

Imaging Used to Diagnose Fatty Liver Disease

If your blood work is suggestive of liver disease, often the next step is to have some imaging done of the liver. The most common type of imaging done is an ultrasound of the liver, as this works well to see if there are fatty deposits in the liver. If greater than 5% of the liver is made up of fatty deposits, this is consistent with fatty liver disease.

If there are concerning findings on the imaging such as evidence of scarring or cancer of the liver, additional imaging tests like CT scans and MRIs can be done as well. 

There are also new tests that have recently come out that work well to gather more information about the liver. One of these tests is called Transient Elastography, and it’s an ultrasound-based test that measures the stiffness of the liver to see how much scarring is present. 

Liver Biopsy To Diagnose Fatty Liver Disease

In patients with MASLD, sometimes I may recommend a liver biopsy to see if there is evidence of advancement to MASH or other advanced liver disease. At this time, a liver biopsy is the only method available to diagnose MASH.

Because a liver biopsy can be a painful procedure, I only recommend it to patients that already have MASLD and are at an increased risk of having or developing MASH. 

How Is Fatty Liver Disease Treated?

The treatment of fatty liver disease depends on many factors, including the type of liver disease and the primary cause. There has been quite an increase in the amount of people with fatty liver disease, so it’s important to understand exactly what may be causing it so that we can better treat it.

In my next few blogs, we’ll be discussing the different ways I treat fatty liver disease in my patients. We’ll also be discussing specific things in our foods and environments that can cause fatty liver disease. By knowing what substances are harmful to the liver, you can make small changes each day to not only protect your liver but improve your overall health.