Fatty Liver Disease Now Affects 4 in 10 US Adults

Your liver is like a busy factory, working tirelessly to process everything you eat and drink. It performs various functions like filtering toxins, producing essential substances and helping digest food. But when this factory becomes clogged with fat, its ability to function properly is severely affected. This is what happens in fatty liver disease, a condition where excess fat accumulates in the liver.

Fatty liver disease is becoming increasingly common, with 4 out of 10 American adults now affected.¹ This makes it more important than ever to understand this condition and its potential impact on your health.

While conventional medicine divides fatty liver disease into nonalcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) and alcoholic fatty liver disease (ALD), they are still the same disease.

The key difference between them lies in the cause. While ALD is directly caused by excessive alcohol consumption, NAFLD/MASLD is not — rather, it occurs because of metabolic dysfunction.² In 2023, the term NAFLD was replaced with MASLD (metabolic dysfunction-associated steatotic liver disease) to more accurately highlight its root cause.³

But again, my preferred way of describing this condition is simply fatty liver disease. The additional attribution to cause is just medical jargon that provides no additional information about the condition itself, and all three are synonyms for fatty liver disease.

MASLD vs. ALD — Understanding the Causal Differences

MASLD is a condition where fat builds up in the liver of people who don’t drink excessive amounts of alcohol. It’s a spectrum of diseases, ranging from simple steatosis, which is just the presence of extra fat in the liver, to metabolic dysfunction associated steatohepatitis or MASH (previously called nonalcoholic steatohepatitis, or NASH).

MASH is a more serious form where the liver becomes inflamed, leading to damage. This inflammation is what sets MASH apart and makes it a greater health risk, as it can cause liver scarring and cirrhosis.⁴

MASLD is closely linked to metabolic syndrome, a cluster of conditions that often occur together. These include obesity, Type 2 diabetes, high blood pressure and high cholesterol. Metabolic syndrome significantly increases the risk of developing MASLD. It’s like a perfect storm of health issues that puts extra stress on the liver. The presence of metabolic syndrome makes it more likely that simple fat accumulation in the liver will progress to MASH.⁵

Alarmingly, MASLD is becoming increasingly common in children and adolescents, with some reports saying it’s now as prevalent as childhood asthma.⁶ MASLD affects up to 9.6% of American children aged 2 to 19 and 17.3% of 15- to 19-year-olds today.⁷

This rise is largely attributed to the increase in childhood obesity and poor dietary habits, such as consuming large amounts of sugary drinks and processed foods. This is a significant concern, as it means that liver damage can begin at a young age, leading to long-term health problems.

One of the most concerning aspects of MASLD is that it often has no noticeable symptoms in its early stages. This is why it’s sometimes called a “silent” disease. People can have MASLD for years without knowing it, until significant liver damage has already occurred.

As its name suggests, alcoholic fatty liver disease (ALD) — also called alcohol-associated liver disease or AALD — is liver damage caused by excessive alcohol consumption. When you drink alcohol, your liver works hard to process it. However, excessive drinking overwhelms the liver, leading to fat accumulation. This buildup of fat is the first stage of ALD.

ALD progresses through several stages. It starts with simple steatosis, then can progress to alcoholic hepatitis, which involves inflammation of the liver. If alcohol consumption continues, this can lead to cirrhosis, a severe condition where the liver becomes permanently scarred. Cirrhosis can cause to liver failure and other serious health complications.⁸

The amount of alcohol that increases the risk of ALD varies from person to person. However, general guidelines suggest that heavy drinking significantly increases the risk. For men, this is typically defined as having more than five drinks on any single day or 15 drinks (or more) per week.

For women, it’s having more than four drinks on any single day or eight (or more) drinks per week.⁹ It is important to remember that for people with underlying liver conditions, there is no safe level of alcohol consumption.

The good news is that in the early stages, ALD can be reversed by stopping alcohol consumption. This allows the liver to heal and recover. However, if alcohol use continues and the disease progresses to cirrhosis, the damage is usually irreversible.¹⁰ This highlights the importance of early intervention and making healthy choices regarding alcohol intake.

Fatty Liver Disease Is on the Rise in America

Fatty liver disease is rapidly emerging as a significant public health challenge in the United States. Recent reports and studies paint a concerning picture of its increasing prevalence, affecting a substantial portion of the American population.

A comprehensive 2024 study published in the journal Communications Medicine reviewed the complex interplay of factors contributing to the development and progression of fatty liver disease.¹¹ The researchers looked at 2017 to 2018 data from 5,532 individuals with a mean age of 45.4 years, and explored the intricate relationship between genetic predispositions, environmental influences and lifestyle factors, particularly dietary habits.

They found that by 2018, 42% of adults had some form of fatty liver disease — higher than prior estimates. Hispanic adults in particular were at high risk, with 47% affected.

The study emphasizes that while genetic factors can increase an individual’s susceptibility to fatty liver disease, environmental factors, such as readily available processed foods and sedentary lifestyles, play a crucial role in triggering and accelerating the disease’s development.

In a university press release, Dr. Juan Pablo Arab, a liver specialist at Virginia Commonwealth University’s Institute for Liver Disease and Metabolic Health and the study’s lead author, said:

“This study highlights a significant health issue that affects a large portion of the U.S. population, and it shows that certain groups are at a higher risk. We hope these findings will guide more targeted health interventions to reduce the burden of liver disease, especially in high-risk communities.”¹²

The Obesity-Fatty Liver Connection

Obesity is a major driver of fatty liver disease. Excess body fat, especially visceral fat (the fat stored around the abdomen), is strongly linked to increased fat deposition in the liver. This excess fat overwhelms the liver’s ability to process it efficiently, leading to its accumulation within liver cells. The more visceral fat you have, the greater your risk of developing fatty liver disease.¹³

Obesity often leads to insulin resistance, a condition where your body’s cells doesn’t respond properly to insulin, the hormone that helps regulate blood sugar levels. When cells become resistant to insulin, blood sugar levels rise, and your body produces more insulin in an attempt to compensate. This excess insulin can promote fat storage in the liver, contributing to fatty liver disease. This insulin resistance is a key link between obesity and fatty liver.¹⁴

Excess fat in the liver can trigger inflammation and oxidative stress, which are harmful processes that can damage liver cells. This inflammation is a key step in the progression from simple steatosis to MASH. Oxidative stress, an imbalance between harmful free radicals and the body’s ability to counteract them, further contributes to liver damage.¹⁵

Dietary patterns play a significant role in both obesity and fatty liver disease. High-calorie diets, particularly those high in processed foods, sugary drinks and unhealthy fats promote both conditions. These types of diets provide excess calories that are easily converted to fat and stored in the liver. Limiting these types of food and focusing on a balanced diet is very important.

Even modest weight loss can significantly improve liver health in people with fatty liver. According to one study, losing just 7% to 10% of body weight can reduce liver fat, improve liver function and decrease inflammation.¹⁶ This shows that even small changes can make a big difference in liver health. Losing weight can also help improve insulin sensitivity.

Dietary changes are crucial for both weight management and liver health. A balanced diet rich in fresh fruits, well-cooked vegetables, whole grains, lean protein and healthy fats is recommended. It’s also important to limit processed foods, sugary drinks and unhealthy fats (including vegetable oils). This type of diet provides the necessary nutrients without overloading the liver with excess fat and sugar.

Regular exercise is another important component of managing fatty liver disease. Being physically active helps improve insulin sensitivity, reduce liver fat and promote weight loss. Even moderate exercise, like brisk walking for 30 minutes most days of the week, can have significant benefits.

Other Factors Taking Control of Your Liver Health

While obesity and alcohol are major risk factors for fatty liver disease, other health conditions can also increase your risk. One example is Type 2 diabetes. Both conditions share risk factors like insulin resistance and metabolic syndrome.

People with Type 2 diabetes are much more likely to develop fatty liver disease, and studies have shown a bidirectional relationship, meaning that fatty liver disease can also worsen insulin resistance and contribute to the development of Type 2 diabetes.^17,18

Having abnormal blood lipid levels, such as high cholesterol and triglycerides, can also contribute to fat accumulation in the liver. When these levels are elevated, it can promote fat storage in the liver, increasing the risk of fatty liver. Managing these lipid levels through diet, exercise and healthy lifestyle habits is important for liver health.¹⁹

Polycystic ovary syndrome (PCOS) is also linked to an increased risk of fatty liver disease. Women with PCOS often have insulin resistance and other metabolic abnormalities that contribute to liver fat accumulation. This link highlights the complex interplay between hormones, metabolism and liver health.^20,21

Addressing sleep apnea, a sleep disorder characterized by pauses in breathing during sleep, is also an important part of liver health as it also contributes to fatty liver disease. These breathing interruptions can lead to low oxygen levels and other metabolic changes that promote liver fat accumulation.²²

If left untreated, fatty liver disease can progress to cirrhosis which increases your risk of liver cancer, also known as hepatocellular carcinoma.²³ fatty liver disease is also linked to an increased risk of cardiovascular disease, including heart disease and stroke.²⁴ This connection is likely due to shared risk factors like insulin resistance, inflammation and metabolic syndrome. Hence, managing liver health also benefits your heart health.

Early detection and management of fatty liver disease are crucial for preventing serious complications. By identifying risk factors and making lifestyle changes, it is possible to slow or even reverse the progression of the disease. This is why regular checkups are so important.

Strategies to Address Fatty Liver Disease at Its Root

Several methods are used to diagnose fatty liver disease. Liver function blood tests can detect elevated liver enzymes that are released into the bloodstream when the liver is damaged. Having elevated levels indicates liver inflammation or other liver problems.

Imaging tests, such as ultrasound, CT scans or MRI, help visualize fat accumulation in the liver. Aside from confirming a diagnosis of fatty liver disease, they also help rule out other liver conditions. In some cases, a liver biopsy may be necessary to confirm the diagnosis of NASH and assess the severity of liver damage. This is a more invasive procedure, although it’s only done when other tests are inconclusive.

Emerging non-invasive tests, such as FibroScan, are also being used to assess liver stiffness, which can indicate the presence of fibrosis (scarring).²⁵ These tests are less invasive than a liver biopsy and can provide valuable information about liver health.

As mentioned, adopting healthy lifestyle habits, such as being physically active and eating a balanced diet, will help address the root causes of metabolic dysfunction to reduce your risk of Fatty liver disease and promote optimal liver function. Keep these tips in mind: