Our liver is a resilient and hardworking organ, performing hundreds of vital functions, from filtering toxins to aiding in digestion. While liver damage is often associated with alcohol abuse or viral infections, a new and silent epidemic is on the rise, one that is intrinsically linked to our metabolic health. This condition is known as Steatotic Liver Disease, and its most dangerous form is Metabolic Dysfunction-Associated Steatohepatitis (MASH).

You may have previously heard of this condition by its older name, Nonalcoholic Steatohepatitis (NASH). Global liver experts recently updated the name to more accurately reflect its true cause: metabolic dysfunction. MASH is a serious disease where excess fat buildup in the liver leads to inflammation and cell damage. It is a “silent” disease, often causing no symptoms for years until significant, irreversible damage has occurred. Understanding this condition is crucial, as it is largely preventable and often reversible in its early stages through dedicated lifestyle changes.

To understand MASH, it is important to see it as part of a spectrum of Steatotic Liver Disease (SLD), a condition characterized by the abnormal accumulation of fat in the liver cells.

The progression typically occurs in stages:

1. Simple Steatosis (Fatty Liver): This is the first stage, where more than 5% of the liver’s weight is composed of fat. At this point, there is fat buildup but little to no inflammation or liver damage. For many, the condition does not progress beyond this stage.
2. Metabolic Dysfunction-Associated Steatohepatitis (MASH): This is the more severe and dangerous form. The “steato-” refers to the fat, and “-hepatitis” means inflammation of the liver. In MASH, the excess fat creates a toxic environment that leads to chronic inflammation and injury to the liver cells.
3. Fibrosis: In response to the chronic inflammation, the liver tries to heal itself by forming scar tissue. This process is called fibrosis.
4. Cirrhosis: If the inflammation and damage continue unchecked, the scar tissue can become widespread and severe, disrupting the liver’s normal structure and function. This advanced, irreversible scarring is known as cirrhosis, which can lead to liver failure and liver cancer.

A helpful analogy is to think of your liver as a high-performance factory. In simple fatty liver, it is as if a few extra, unused boxes are being stored in the corners. It is a bit cluttered, but the factory’s work continues normally. In NASH, those boxes are not just stored; they are leaking an irritating substance that is causing a constant state of alarm (inflammation). The factory’s “fire sprinklers” are always on, causing progressive damage to the vital machinery and walls. This inflammation and damage is MASH.

In my experience, many patients don’t know they have MASH until it shows up on blood tests or imaging. It’s often silent until liver damage is already progressing, making early screening essential for those at risk.

The root cause of MASH is metabolic dysfunction. It is considered the liver’s manifestation of Metabolic Syndrome, a cluster of conditions that increase the risk of heart disease, stroke, and type 2 diabetes. The central driver of this dysfunction is insulin resistance.

Insulin is a hormone that helps your body’s cells take up glucose (sugar) from the blood to use for energy. In insulin resistance, the cells do not respond properly to insulin’s signal. To compensate, the pancreas pumps more insulin. This state of high insulin levels signals the liver to go into overdrive. It takes in more fat from the bloodstream and ramps up its own production of fat from excess carbohydrates and sugars.

This leads to the initial buildup of fat (steatosis). In individuals who progress to MASH, this excess fat within the liver cells becomes unstable and undergoes oxidative stress. This process generates damaging molecules called free radicals, which damage liver cells. This cellular injury then triggers a chronic inflammatory response from the immune system, leading to the hepatitis component of MASH and paving the way for the development of scar tissue (fibrosis).

Patients often feel shocked when they learn their liver is damaged, especially if they don’t drink. But the truth is, MASH is driven by modern lifestyles more than alcohol, and many don’t feel symptoms until damage is advanced.

A person develops MASH when they have the underlying metabolic conditions that promote fat accumulation and inflammation in the liver. It is not a contagious disease. The risk factors for MASH are the same as those for metabolic syndrome.

The most significant risk factors include:

• Overweight or Obesity: This is the strongest risk factor, particularly having excess abdominal or visceral fat.
• Type 2 Diabetes or Prediabetes: The insulin resistance that defines these conditions is a primary driver of MASH.
• Dyslipidemia: This refers to abnormal levels of fats in the blood, specifically high triglycerides and low HDL (“good”) cholesterol.
• High Blood Pressure (Hypertension).

Having this cluster of conditions, obesity, insulin resistance, high triglycerides, and high blood pressure is known as metabolic syndrome, and it dramatically increases the risk of having MASH. While it is most strongly linked to these factors, it is important to note that some lean individuals with other signs of insulin resistance can also develop the condition.

I often tell patients that MASH is the liver’s way of crying out when the body’s metabolic system is overwhelmed, especially in people with diabetes or obesity, even if they feel fine.

The most dangerous aspect of MASH is that it is a “silent” disease. In its early and even moderately advanced stages, it typically causes no noticeable symptoms at all. A person can have significant inflammation and even early scarring in their liver and feel completely fine. This is why it often goes undiagnosed for years until the liver damage is severe.

When symptoms do finally occur, they are often vague and non-specific. These can include:

• Profound fatigue and malaise.
• A dull, aching pain or feeling of fullness in the upper right side of the abdomen, where the liver is located.
• Unexplained weight loss.

If MASH is left untreated and progresses to advanced cirrhosis, the signs and symptoms of liver failure will appear. These are much more severe and include:

• Jaundice (yellowing of the skin and eyes).
• Ascites (a large buildup of fluid in the abdomen).
• Edema (swelling in the legs and ankles).
• Easy bruising and bleeding.
• Hepatic encephalopathy (confusion, drowsiness, or slurred speech caused by the buildup of toxins in the brain).

In the clinic, I’ve seen many MASH patients who were completely asymptomatic, but their liver enzymes told a different story. It’s been a “silent storm” building for years.

Because MASH is usually asymptomatic, it is often first suspected as an incidental finding. A person might have routine blood work done for another reason, which reveals unexplained elevated liver enzymes (specifically ALT and AST). This finding should prompt a further investigation.
Diagnosing MASH involves ruling out other liver diseases and confirming fatty liver with inflammation.

1. Blood Tests: In addition to liver function tests, a doctor will order tests to rule out other causes of liver disease, such as screening for viral hepatitis (Hepatitis B and C), checking for autoimmune markers, and assessing iron levels.
2. Imaging Studies: Non-invasive imaging can detect fat in the liver and assess scarring.
   • Abdominal Ultrasound: This is often the first imaging test. It can easily show the presence of excess fat in the liver, but it cannot distinguish simple fatty liver from MASH inflammation.
   • FibroScan® (Transient Elastography): This is a specialized ultrasound-based test that measures liver stiffness. A stiffer liver indicates more significant fibrosis or scarring.
   • MRI: An MRI can also be used to quantify the amount of fat and fibrosis in the liver.
3. Liver Biopsy: In this procedure, a doctor uses a long, thin needle to take a tiny sample of liver tissue. A pathologist then examines the sample under a microscope to confirm the presence of the three key features: fat (steatosis), inflammation, and liver cell injury (ballooning). The biopsy also allows precise staging of fibrosis.

Liver biopsy remains the gold standard, but it’s invasive. I rely heavily on non-invasive tests and risk scores first, especially for patients with metabolic risk factors.

There is no FDA-approved medication specifically for MASH, but treatment focuses on reversing risk factors and slowing liver damage.

1. Weight Loss

This is the single most impactful intervention for treating MASH.

• Losing just 3-5% of total body weight can reduce the amount of fat in the liver.
• Losing 7-10% of total body weight can significantly reduce liver inflammation and can even lead to the reversal of fibrosis in some individuals (American Liver Foundation, 2023).
• Weight loss should be achieved gradually through a combination of diet and exercise. Rapid weight loss can actually worsen liver inflammation.

2. Healthy Diet

There is no single “MASH diet.” The focus should be on a healthy, balanced eating pattern that promotes weight loss and reduces metabolic stress.

• The Mediterranean diet, which is rich in fruits, vegetables, whole grains, nuts, and healthy fats like olive oil, and low in red meat and processed foods, is often recommended.
• Crucially, it is vital to eliminate or strictly limit added sugars, especially sugar-sweetened beverages and high-fructose corn syrup, which are major drivers of liver fat production.
• Limiting saturated and trans fat intake is also important.

3. Physical Exercise

Regular physical activity is key. It helps with weight loss, improves insulin sensitivity, and may have direct anti-inflammatory effects on the liver. The goal should be at least 150 minutes of moderate-intensity aerobic exercise (like brisk walking, cycling, or swimming) per week, combined with some resistance training.

4. Managing Associated Conditions

• Strict control of type 2 diabetes and blood pressure.
• Managing cholesterol levels.
• Completely avoiding alcohol, as it can add further injury to an already inflamed liver.

5. Medications

This is one of the most active areas of pharmaceutical research.

• Some diabetes medications, like pioglitazone, and high-doses of Vitamin E are sometimes used “off-label” by specialists as they have been shown to improve liver histology in some patients (NIDDK, 2022).
• Newer classes of drugs, including GLP-1 receptor agonists (used for diabetes and weight loss) and others targeting specific inflammatory or fibrotic pathways, are showing great promise in clinical trials.

I’ve seen real improvement in patients who commit to weight loss, sometimes even reversing fibrosis. It’s a lifestyle-driven disease, and fortunately, that means lifestyle can help heal it.

Nonalcoholic Steatohepatitis (NASH), now known as MASH, has emerged as a silent but formidable public health crisis, marching in lockstep with the global epidemics of obesity and type 2 diabetes. Its danger lies in its silence; it causes no symptoms for years while progressively damaging the liver, potentially leading to cirrhosis and liver cancer. However, a diagnosis of MASH should not be seen as a final verdict, but as an urgent call to action. It is a largely preventable and often reversible condition. What I always tell patients is this: MASH might sound scary, but you’re not powerless. With the right changes, your liver has the ability to recover, step by step, meal by meal, walk by walk.

1. American Liver Foundation. (2023). NASH (Nonalcoholic Steatohepatitis). Retrieved from https://liverfoundation.org/liver-diseases/fatty-liver-disease/nash-nonalcoholic-steatohepatitis/
2. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). (2022). Nonalcoholic Fatty Liver Disease & NASH. Retrieved from https://www.niddk.nih.gov/health-information/liver-disease/nafld-nash
3. Mayo Clinic. (2024). Nonalcoholic fatty liver disease. Retrieved from https://www.mayoclinic.org/diseases-conditions/nonalcoholic-fatty-liver-disease/symptoms-causes/syc-20354567