Metabolic Dysfunction–Associated Steatotic Liver Disease (MASLD)

Metabolic dysfunction–associated steatotic liver disease (MASLD) and metabolic dysfunction–associated steatohepatitis (MASH) are updated medical terms for conditions previously known as non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) (Tilg et al., 2025).

These newer terms emphasize what research clearly shows: fatty liver disease in most people is closely linked to metabolic health, including body weight, blood sugar regulation, cholesterol levels, and blood pressure (Huang et al., 2025; Cusi et al., 2025).

MASLD refers to excess fat in the liver plus at least one metabolic risk factor (Tilg et al., 2025).
MASH is a more advanced form of MASLD, where liver fat is accompanied by inflammation, liver cell injury, and scarring (fibrosis) (Sanyal et al., 2021).

MASLD affects roughly 1 in 4 adults worldwide and is now one of the most common causes of chronic liver disease in Canada and globally (Huang et al., 2025).

Many people with MASLD or early MASH have no symptoms, which is why these conditions are often discovered incidentally during routine blood work or imaging (Tilg et al., 2025).

When symptoms are present, they may include:

• Fatigue or low energy
• Mild discomfort or fullness in the upper right abdomen
• General feeling of being unwell

As liver disease progresses to advanced fibrosis or cirrhosis, more serious symptoms may occur:

• Swelling of the legs or abdomen
• Yellowing of the skin or eyes (jaundice)
• Easy bruising or bleeding
• Confusion or difficulty concentrating (Sanyal et al., 2021)

Anyone experiencing these symptoms should seek medical care promptly.

Who is at Risk?

You may be at higher risk of developing MASLD or MASH if you have one or more of the following:

• Overweight or obesity, especially excess abdominal fat
• Type 2 diabetes or prediabetes
• High blood pressure
• High triglycerides or low HDL (“good”) cholesterol
• Metabolic syndrome
• Sedentary lifestyle
• Diets high in sugary drinks, refined carbohydrates, and ultra-processed foods (Cusi et al., 2025; Tilg et al., 2025)

Importantly, MASLD can also occur in people who are not visibly overweight or have a normal BMI if insulin resistance or other metabolic risk factors are present (Huang et al., 2025).

Diagnosing MASLD and MASH usually involves a combination of medical history, blood tests, and imaging (Tacke et al., 2024).

Medical History and Physical Exam

Health-care providers may assess:

• Weight and waist circumference
• History of diabetes, high blood pressure, or abnormal cholesterol
• Alcohol intake
• Family history of liver disease (Tilg et al., 2025)

Blood Tests

Common tests include:

• Liver enzymes (ALT, AST)
• Other liver function tests
• Blood glucose and HbA1c
• Cholesterol and triglycerides

Important: Liver enzymes can be normal even in advanced disease, so normal results do not rule out MASLD or MASH (Tilg et al., 2025).

Imaging

• Ultrasound: Can detect moderate to severe liver fat but is less sensitive for early disease and fibrosis
• Transient elastography (FibroScan®): Measures liver stiffness (fibrosis) and estimates liver fat (Tacke et al., 2024)

Non-Invasive Fibrosis Scores

Blood-based scores such as FIB-4 or the NAFLD fibrosis score help estimate the risk of advanced scarring and are commonly used in clinical practice (Tacke et al., 2024).

Liver Biopsy (Selected Cases)

A liver biopsy may be recommended in specific situations to confirm MASH or accurately stage fibrosis, but it is not required for everyone (Sanyal et al., 2021).

There is no single medication that cures MASLD or MASH, but many people improve significantly with lifestyle-based treatment, particularly when disease is identified early (Cusi et al., 2025).

Core Treatment Goals

• Reduce liver fat and inflammation
• Prevent or slow liver scarring
• Improve overall metabolic and cardiovascular health

Treatment May Include

• Weight management: Losing about 7–10% of body weight can substantially reduce liver fat and inflammation and may improve fibrosis (Sanyal et al., 2021)
• Nutrition therapy: A Mediterranean-style eating pattern emphasizing vegetables, fruits, whole grains, legumes, nuts, olive oil, and fish (Huang et al., 2025) Learn more about nutrition here.
• Physical activity: At least 150 minutes per week of moderate-intensity activity, plus resistance training when possible
• Management of diabetes and blood lipids: Through diet, lifestyle, and medications when appropriate (Cusi et al., 2025)
• Limiting or avoiding alcohol, especially in advanced disease (Tacke et al., 2024)

Some newer diabetes and weight-management medications may also improve liver markers in select individuals, under medical supervision (Cusi et al., 2025).

How Does MASLD Progress to MASH?

Not everyone with MASLD develops MASH. When progression occurs, it is usually driven by several overlapping processes:

• Insulin resistance increasing fat delivery to the liver
• Toxic effects of certain fats on liver cells
• Chronic inflammation and oxidative stress
• Formation of scar tissue (fibrosis) (Huang et al., 2025)

Fibrosis stage is the strongest predictor of long-term outcomes. People with MASH tend to progress more quickly than those with simple fatty liver (Sanyal et al., 2021).

Is MASLD or MASH reversible?

Yes, both are reversible. Once liver fibrosis occurs, it can be permanent, which is why prevention and early treatment is so important.

What can I do if I’m diagnosed with MASLD or MASH?

Working with a health-care team, including a registered dietitian, can help translate medical recommendations into practical, sustainable changes (Huang et al., 2025).

Helpful strategies include:

• Choosing whole, minimally processed foods most of the time
• Reducing sugary drinks and refined carbohydrates
• Including regular movement throughout the day
• Setting realistic, step-by-step goals rather than aiming for rapid weight loss

When Should You See a Health-Care Provider?

You should consider medical evaluation if you:

• Have type 2 diabetes, prediabetes, obesity, high cholesterol, or high blood pressure
• Have been told you have a “fatty liver” on imaging
• Have abnormal liver blood tests
• Have a family history of liver disease
• Experience symptoms such as fatigue, abdominal discomfort, swelling, or jaundice (Tilg et al., 2025)

Early identification allows time to slow, stop, or even reverse liver damage, often before serious complications develop (Sanyal et al., 2021).

References

Cusi, K., Anstee, Q. M., Beaton, M. D., Boursier, J., Bugianesi, E., Loomba, R., … Sanyal, A. J. (2025). Metabolic dysfunction–associated steatotic liver disease (MASLD) in people with diabetes: The need for screening and early intervention. Diabetes Care.

Huang, D. Q., Nguyen, M. H., Lee, J., Younossi, Z. M., & Global MASLD Consortium. (2025). Metabolic dysfunction–associated steatotic liver disease: Global burden, natural history, and treatment strategies. Hepatology.

Sanyal, A. J., Harrison, S. A., Bass, N. M., Abdelmalek, M. F., Diehl, A. M., Caldwell, S., … Neuschwander-Tetri, B. A. (2021). Prospective study of outcomes in adults with nonalcoholic fatty liver disease. New England Journal of Medicine, 385(17), 1559–1569.

Tacke, F., Vonghia, L., Castera, L., Eslam, M., Newsome, P. N., Targher, G., … European Association for the Study of the Liver. (2024). EASL–EASD–EASO clinical practice guidelines on the management of metabolic dysfunction–associated steatotic liver disease (MASLD). Journal of Hepatology.

Tilg, H., Petta, S., Stefan, N., & Targher, G. (2025). Metabolic dysfunction–associated steatotic liver disease in adults. JAMA.