MASLD, or metabolic dysfunction-associated steatotic liver disease, is the current name for what was previously called nonalcoholic fatty liver disease (NAFLD). It describes a condition where excess fat builds up in the liver, driven by metabolic problems like obesity, high blood sugar, or abnormal cholesterol levels. MASLD affects more than 30% of the global population, making it one of the most common chronic liver conditions in the world.
Why the Name Changed From NAFLD
For decades, “nonalcoholic fatty liver disease” was the standard term. But the name had real problems. It defined the condition by what it wasn’t (not caused by alcohol) rather than what it was. It also used the word “fatty,” which many patients and clinicians found stigmatizing. In a large international survey of experts, 61% considered “nonalcoholic” potentially stigmatizing, and 66% felt the same about “fatty.”
Beyond the language issues, the old name created clinical blind spots. NAFLD was a diagnosis of exclusion: if you drank more than a small amount of alcohol, you didn’t qualify, even if metabolic dysfunction was clearly driving your liver disease. That meant many patients at high risk for serious outcomes were shut out of research trials and treatment pathways. A global effort led by the American Association for the Study of Liver Diseases, the European Association for the Study of the Liver, and other organizations developed the new terminology to reflect what actually causes the disease and to remove stigmatizing language.
How MASLD Is Diagnosed
A MASLD diagnosis requires two things: evidence of fat accumulation in the liver (usually found on imaging like an ultrasound) and at least one cardiometabolic risk factor. Those risk factors are:
- Overweight or obesity: a BMI above 25 (or above 23 in Asian populations), or a waist circumference over 94 cm for men or 80 cm for women
- Elevated blood sugar: fasting glucose above 100 mg/dL, an HbA1c above 5.7%, or a type 2 diabetes diagnosis
- High blood pressure: above 130/85 mmHg, or currently taking blood pressure medication
- High triglycerides: above 150 mg/dL, or currently on lipid-lowering therapy
- Low HDL cholesterol: below 40 mg/dL for men or below 50 mg/dL for women, or currently being treated for it
You only need one of those five to qualify. Given how common these metabolic issues are, most people with liver fat will meet the threshold. The diagnosis also requires that daily alcohol intake stays below 30 grams for men and 20 grams for women (roughly two standard drinks or fewer for men, about one and a half for women). People who drink moderately above those limits but still have metabolic risk factors fall into a related category called MetALD, which covers the overlap between metabolic and alcohol-related liver disease.
What Happens Inside the Liver
In its earliest stage, MASLD involves simple fat buildup in liver cells, sometimes called steatosis. Many people stay at this stage for years without symptoms or complications. But in a significant number of cases, the liver becomes inflamed. When inflammation combines with damage to liver cells (a process called ballooning), the condition has progressed to MASH, or metabolic dysfunction-associated steatohepatitis. MASH is the more serious form and the one most likely to cause lasting harm.
In a study tracking patients over a median of 10 years, about half showed clinical progression of their disease. Among those who started with simple fat accumulation rather than full-blown MASH, 70% met MASH criteria by their follow-up biopsy. Having high blood pressure or elevated liver enzymes at baseline made progression more likely. The takeaway: MASLD is not always a static, harmless condition. It can quietly worsen over time.
Long-Term Risks: Cirrhosis and Liver Cancer
The main concern with MASLD is what it can become. Ongoing inflammation and cell damage lead to fibrosis, where scar tissue gradually replaces healthy liver tissue. Advanced fibrosis can progress to cirrhosis, a state where the liver is so scarred it struggles to function. In a large U.S. healthcare analysis spanning 2010 to 2021, the annual incidence of MASLD-related cirrhosis rose by 37.5%. Liver cancer (hepatocellular carcinoma) linked to MASLD increased even more dramatically, with incidence climbing 175% over the same period.
These numbers reflect both the growing prevalence of MASLD and the fact that many cases go undetected until significant damage has already occurred. Most people with early-stage MASLD feel perfectly fine. There is no pain, no obvious warning sign. That’s what makes screening and risk assessment so important, particularly for people who already have diabetes, obesity, or other metabolic conditions.
How Liver Scarring Is Assessed
Liver biopsy remains the most definitive way to evaluate fibrosis, but it’s invasive and not practical for screening large numbers of people. Instead, doctors commonly use a blood-based calculation called the FIB-4 index, which combines your age, platelet count, and two liver enzyme levels into a single score. A FIB-4 below 1.3 (or below 2.0 if you’re over 65) suggests a low risk of advanced scarring. A score above 2.67 suggests a higher risk and typically prompts further evaluation, such as specialized imaging that measures liver stiffness.
This tiered approach lets doctors identify which patients need closer monitoring without subjecting everyone to invasive procedures. If your score falls in the middle, additional testing helps clarify where you stand.
Weight Loss as Treatment
Lifestyle changes remain the most effective and most accessible treatment for MASLD. Weight loss, specifically, has dose-dependent benefits. Losing at least 5% of your total body weight is associated with reduction in liver fat. Losing 7% is linked to resolution of MASH, meaning the inflammation and cell damage can reverse. Reaching 10% or more body weight loss leads to fibrosis regression in up to 80% of patients. Those are striking numbers for a condition with limited pharmaceutical options.
The type of weight loss matters less than the amount. A combination of dietary changes and regular physical activity is the standard recommendation, though the specific approach can be tailored to what’s sustainable for you. Even modest improvements in diet quality, particularly reducing sugar-sweetened beverages and refined carbohydrates, benefit liver fat independently of weight change.
The First Approved Medication for MASH
For years, there was no FDA-approved drug specifically for this liver disease. That changed with resmetirom, a once-daily pill that works by activating thyroid hormone receptors in the liver, which helps the liver clear excess fat and reduce inflammation. In a large Phase 3 trial published in the New England Journal of Medicine, about 30% of patients taking the higher dose achieved resolution of their liver inflammation with no worsening of scarring, compared to roughly 10% on placebo. Around 26% saw their fibrosis improve by at least one stage, compared to 14% on placebo.
These results are meaningful but modest. The drug doesn’t work for everyone, and it’s currently indicated for people who already have MASH with significant fibrosis, not for the broader population with early-stage MASLD. It represents a first step in pharmaceutical treatment rather than a cure.
Who Should Pay Attention
MASLD prevalence varies significantly across populations. In Australia, an estimated 22% of adults have the condition. In Japan, the figure is closer to 9%. In European primary care settings, recorded diagnoses are far lower than what population studies suggest, highlighting a major gap between how many people have MASLD and how many know about it. The condition is dramatically underdiagnosed.
If you have type 2 diabetes, obesity, high blood pressure, or abnormal cholesterol, your risk of MASLD is substantially elevated. Many people discover they have it incidentally, when imaging done for another reason reveals a fatty liver. Because the disease progresses silently, catching it early and addressing the metabolic factors that drive it gives you the best chance of preventing serious liver damage down the line.