If you were told years ago that you had nonalcoholic fatty liver disease, that label no longer exists in the medical literature. In 2023, an international panel of liver specialists renamed the condition metabolic dysfunction-associated steatotic liver disease, or MASLD, and renamed its inflammatory form, once nonalcoholic steatohepatitis, as metabolic dysfunction-associated steatohepatitis, or MASH. The shift is more than a spelling change. It moves the diagnosis from being defined by what a patient does not have to being defined by the metabolic problem actually driving the disease.
Key points#
- NAFLD is now MASLD and NASH is now MASH; both names center on metabolic dysfunction rather than on the absence of alcohol.
- MASLD is diagnosed by positive criteria: liver fat plus at least one of five cardiometabolic risk factors.
- A new category, MetALD, names the common situation of a metabolically driven liver in someone who also drinks meaningfully.
- The change came from a structured four-round consensus of 236 experts across 56 countries, not a single committee.
- A renaming is a scientific claim and can be appraised like any other, by asking who decided, how, and whether it changes patient care.
Naming by cause instead of naming by absence#
The old vocabulary described the liver by exclusion. To call a fatty liver "nonalcoholic," a clinician first had to rule out heavy drinking and a handful of other causes, so the name really announced what a patient did not have. That is an awkward way to define a disease, roughly like calling a headache "non-migraine" and leaving the actual cause unstated.
The new framework flips this. It opens with a wide umbrella term, steatotic liver disease (SLD), meaning fat buildup in the liver from any source. Sitting under that umbrella are the specific diagnoses. MASLD applies when a person has liver fat plus at least one of five cardiometabolic markers: overweight or an enlarged waist, elevated fasting glucose or type 2 diabetes, raised blood pressure, high triglycerides, or low HDL cholesterol. Each marker counts if it crosses a defined threshold or if the person is already being treated for it. MASH is the more aggressive, inflamed version, with liver-cell injury that can advance toward fibrosis and cirrhosis. A leftover bin, cryptogenic SLD, holds cases of liver fat with no metabolic or alcohol explanation at all.
The important design choice is that MASLD is a diagnosis of inclusion. According to the multisociety statement, a patient now qualifies by meeting positive criteria, and the diagnosis is allowed to sit alongside other liver conditions rather than being ruled out the moment another cause appears.
MetALD: a name for the overlap clinicians already saw#
The single most useful addition may be MetALD, short for metabolic and alcohol-related liver disease. It describes a person every primary care office recognizes: someone who clearly meets the metabolic criteria for MASLD and who also drinks more than a token amount. Before, that patient had no clean home. They were forced into either the "nonalcoholic" box, which was inaccurate, or the alcohol-related box, which ignored their metabolic disease.
The consensus drew the overlap zone at roughly 20 to 50 grams of alcohol per day for women and 30 to 60 grams per day for men (about 140 to 350 grams per week for women and 210 to 420 for men). Below that intake, with cardiometabolic risk present, the diagnosis stays MASLD. Above it, the condition is treated as predominantly alcohol-related.
MetALD matters because the two drivers do not simply sit side by side. Alcohol and metabolic dysfunction can each speed up scarring in the liver, and lumping these patients into one pure category or the other hid that combined load in both research and clinics. Giving the overlap a name turns it into something researchers can count, follow, and study on its own terms.
Why rename a condition people had learned to recognize#
Two arguments carried the vote. The first was stigma. In the panel's own surveys, most participants judged the word "fatty" to be stigmatizing, and a majority disliked defining an illness by "nonalcoholic," a phrase that can read as accusatory to patients and dismissive of a serious disease. The second was accuracy. The underlying biology is metabolic, rooted largely in insulin resistance, so a name anchored to that biology communicates cause rather than a negative.
This was a deliberate process rather than a back-room decision. The panel used a modified Delphi method: 236 participants from 56 countries worked through four rounds of surveys, with a supermajority threshold of 67 percent required to declare agreement. That structure is part of why journals and professional societies took up the new terms so quickly.
Reading a renaming with a skeptical eye#
A disease renaming is a scientific claim about how a condition should be divided up, and it deserves the same scrutiny as any other claim. This is the kind of question that also sits at the heart of clinical epidemiology and evidence appraisal, where the exact wording of a definition can reshape who counts as a case. A few questions travel well here.
Who decided, and how? Consensus is a method with real limits. A Delphi process reduces the loudest-voice problem, but a 67 percent supermajority also means a meaningful minority of experts may have disagreed on specific points. It is fair to ask whether each criterion was validated against patient outcomes or simply settled by vote. Here, the categories were fixed by expert agreement first and are now being tested against real-world cohorts.
Does the label change who gets diagnosed? Studies comparing NAFLD and MASLD populations find heavy overlap, with most former NAFLD patients also meeting MASLD criteria. Yet the two groups are not identical, and when a definition shifts even slightly, prevalence numbers, trial eligibility, and the reading of older studies can all move with it. Keeping the evidence base continuous across the old and new names is a legitimate concern the field is tracking closely.
Does it change anything for patients? Often a name is only a name. What makes MASLD useful is that its defining criteria double as its treatment targets: weight, glucose, blood pressure, and lipids are exactly the levers a person and their clinician can work on. That is the practical test for any relabeling. Does it sharpen what to do next, or only what to call it?
For a reader, the honest summary is that this change is well motivated and well documented, and still maturing as researchers confirm that the new categories predict outcomes better than the old ones did.
Sources and further reading
Questions and answers
Is MASLD a different disease from the fatty liver I was told about years ago?
In most cases, no. For the large majority of people previously labeled NAFLD, the same liver picture now meets MASLD criteria. The name and the framing changed; the underlying condition did not.
What does the "MASH" part mean?
MASH is the more active form, where liver fat is accompanied by inflammation and cell injury that can progress to scarring. It replaces the older term NASH and signals a higher-risk stage than simple fat alone.
Why does drinking matter if this is a metabolic disease?
Because both metabolism and alcohol can each harm the liver on their own. The MetALD category exists precisely to describe people driven by both, so their combined risk is not overlooked.