Three of the world’s largest liver associations have agreed on a new way to name a common disease. The change, effective as of June 15, 2023, officially retires the terms “non-alcoholic fatty liver disease” and “non-alcoholic steatohepatitis.” In their place are “metabolic dysfunction–associated steatotic liver disease” (MASLD) and “metabolic dysfunction associated steatohepatitis” (MASH).
The old names had a problem. They defined the disease by what it was not. “Non-alcoholic” told doctors and patients what the cause wasn’t — alcohol — without saying what it actually was. That kind of negative definition made it harder to talk about the condition clearly. It also carried a stigma, implying that patients who drank any alcohol at all somehow brought the disease on themselves. The new terms, by contrast, describe what is happening: fat buildup in the liver linked to metabolic dysfunction.
The decision did not come from a single institution. It was the product of a modified Delphi process, a structured method for reaching expert consensus. The three organizations driving the change were the American Association for the Study of Liver Diseases, the European Association for the Study of the Liver, and the Latin American Association for the Study of the Liver. That kind of cross-continental agreement gives the new terminology weight. It is not a suggestion from one committee. It is a coordinated shift from the major professional bodies that set the standards for liver care.
The new classification system does more than rename old categories. It introduces a third category entirely: “metabolic and alcohol associated liver disease,” or metALD. This describes patients whose liver disease stems from both metabolic issues and alcohol use. The old system forced clinicians to pick one cause or the other, even when both were clearly at play. A patient with obesity who also drank moderately fell into a diagnostic gray zone. MetALD acknowledges that overlap exists and gives doctors a label for it.
Fatty liver disease itself remains a serious and growing public health problem. The condition, also called hepatic steatosis or steatotic liver disease, involves excess fat stored in liver cells. Many people have it and never know. Symptoms are often absent or mild — tiredness, a vague ache in the upper right side of the abdomen. The real danger is what comes later. Untreated, fatty liver can progress to cirrhosis, liver cancer, and esophageal varices, which are swollen veins in the esophagus that can rupture and bleed.
The disease splits into two main subtypes. MASLD covers cases driven by metabolic factors such as obesity, insulin resistance, and high blood lipids. Alcoholic liver disease covers cases driven by chronic heavy drinking. The new metALD category sits between them. This framework gives doctors a clearer picture of what is happening inside a patient’s liver and why.
The renaming effort reflects a broader trend in medicine. Doctors are moving away from labels that define diseases by exclusion. The old name told you what to rule out. The new name tells you what to look for. That shift matters for research, too. Clinical trials for fatty liver drugs previously used the NASH label. Now they will use MASH. The change may seem cosmetic, but it affects how studies are designed, how patients are recruited, and how results are interpreted.
For now, the practical impact on patients is small. The diagnosis remains the same. The treatments remain the same. But the language around the disease has changed. And language shapes how doctors think, how patients understand their condition, and how the public perceives the scale of the problem. Fatty liver disease affects millions of people worldwide. Giving it a clearer name is a small step, but it is a step in the right direction.
