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The English Terminology for Fatty Liver:
A Complete Guide to What These Terms Actually Mean
Covenant Metabolic Specialists
Physician Reviewed
Dec 17, 2025
Overview
“Fatty liver” is one of the most commonly used—but poorly understood—terms in modern medicine. Over the years, the language surrounding this condition has evolved dramatically. What once seemed like a simple definition has become a nuanced vocabulary shaped by new research, shifting clinical guidelines, and the global move toward metabolic health awareness.
For patients, caregivers, and even clinicians outside hepatology, the terminology can feel confusing. Why are we moving away from the word “NAFLD”? What does “MASLD” mean? And why do some people still call it “fatty liver disease”?
This guide breaks down the complete English terminology for fatty liver, explains how these terms relate to one another, and illustrates why the updated language matters for diagnosis, treatment, and patient outcomes.
Table of Contents
Introduction
Why Terminology Matters
Traditional Terms Used in English
Modern, Updated Terms Recommended by International Liver Societies
Key Differences Between MASLD, MASH, NAFLD, and NASH
How Terminology Impacts Screening and Treatment
Why the Shift Toward “Metabolic” Language Is Important
Frequently Asked Questions
Conclusion
Introduction
In English-speaking medicine, “fatty liver” has always been used as an umbrella term to describe excess fat accumulating inside liver cells. But as science progressed, specialists realized that the words we use influence how patients understand their risk and how clinicians identify the disease.
Historically, the conversation centered on eliminating alcohol as the cause. Today, the focus has shifted to the metabolic drivers that affect the vast majority of patients—insulin resistance, obesity, prediabetes, type 2 diabetes, hypertension, and abnormal lipids.
Because of this shift, English terminology has been revised to better match scientific understanding.
Why Terminology Matters
Terminology shapes:
Diagnosis: Clear naming reduces misclassification.
Treatment pathways: Specific terms determine which therapies, lifestyle interventions, and medications are recommended.
Clinical trial eligibility: Pharmaceutical companies rely on precise terminology.
Patient understanding: Many patients ignored “fatty liver” for years because it sounded harmless.
The updated terminology helps people recognize the seriousness of the condition while also removing unnecessary stigma.
Traditional Terms Used in English
Fatty Liver
A general, non-medical English term referring to excess fat in the liver. It does not explain the cause.
Nonalcoholic Fatty Liver Disease (NAFLD)
For decades, NAFLD was the standard English term describing fatty liver not caused by alcohol.
Nonalcoholic Steatohepatitis (NASH)
The more severe form of NAFLD. Characterized by inflammation, ballooning injury of liver cells, and a higher risk of fibrosis and cirrhosis.
Limitations of These Terms
They define the disease by what it is not (non-alcoholic).
They fail to emphasize metabolic dysfunction—the TRUE driver for most patients.
They create stigma, especially for patients worried they will be misjudged regarding alcohol use.
They do not reflect ethnic, genetic, and sex-based differences now known to influence disease.
This led to a major global terminology update.
Modern Terms Recommended by International Liver Societies
In 2023, a coalition of global liver experts including members of the AASLD and EASL updated the terminology.
Below are now the preferred English terms:
MASLD: Metabolic Dysfunction–Associated Steatotic Liver Disease
The new umbrella term replacing NAFLD.
Key defining feature:
At least one cardiometabolic risk factor (e.g., obesity, prediabetes, diabetes, high blood pressure, abnormal cholesterol).
MASH: Metabolic Dysfunction–Associated Steatohepatitis
The modern replacement for NASH.
Represents the inflammatory, more dangerous form of MASLD.
MetALD
A category for individuals who have metabolic dysfunction and consume more alcohol than the MASLD safe threshold but not enough to classify as alcohol-related liver disease.
ALD: Alcohol-Associated Liver Disease
Steatosis or liver injury primarily caused by alcohol.
Cryptogenic Steatotic Liver Disease
Fatty liver without a clearly identifiable metabolic or alcohol-related cause.
Key Differences Between MASLD, MASH, NAFLD, and NASH
Term | Old or New? | What It Means | Why It Matters |
|---|---|---|---|
Fatty Liver | Traditional | Extra fat in liver | Non-specific; not a diagnosis |
NAFLD | Old | Fatty liver not caused by alcohol | Replaced due to stigma & lack of metabolic clarity |
NASH | Old | Severe inflammatory form of NAFLD | Now called MASH |
MASLD | New | Fatty liver driven by metabolic dysfunction | Highlights cardiometabolic risk |
MASH | New | Inflammatory, progressive form of MASLD | Better reflects mechanisms and outcomes |
How Terminology Impacts Screening and Treatment
Better Identification of At-Risk Patients
Under NAFLD, many normal-weight patients and many minorities with cardiometabolic risk were missed. MASLD criteria catch these individuals earlier.
Tailored Treatment
Updated terminology aligns directly with:
Weight-loss therapies
GLP-1 medications
Insulin resistance treatment
Cardiometabolic disease prevention
Clinical Trials
Pharmaceutical companies now classify eligibility using MASLD and MASH, making the terminology essential for advancing new treatments.
Insurance and Coding
Over time, terminology updates shift clinical coding practices, which affects:
Coverage
Diagnosis capture
Referral patterns
Why the Shift Toward “Metabolic” Language Is Important
Metabolic health is now recognized as one of the leading determinants of liver disease worldwide.
The shift:
Removes stigma around alcohol
Aligns with global health priorities (diabetes, obesity, cardiovascular disease)
Supports early intervention by highlighting risk factors patients CAN modify
Reflects the true biology: most fatty liver cases are tied to insulin resistance
By naming the disease accurately, we help patients take it seriously—and take action.
Frequently Asked Questions
Is “fatty liver” the same as MASLD?
Not exactly.
“Fatty liver” just describes fat in the liver; MASLD explains why it’s there—due to metabolic dysfunction.
Why did the terminology change at all?
To remove stigma and clarify the metabolic origin of the disease.
Is MASH more dangerous?
Yes.
MASH includes inflammation and liver injury, which significantly increase the risk of fibrosis, cirrhosis, and liver cancer.
Why do some doctors still use NAFLD or NASH?
Medical terminology takes time to transition across healthcare systems. Many clinicians are shifting gradually.
Conclusion
The English terminology for fatty liver disease has evolved to reflect a deeper scientific understanding of the condition. Moving from NAFLD to MASLD and from NASH to MASH allows healthcare providers to diagnose earlier, communicate more clearly, reduce stigma, and ensure that metabolic risk is front and center—exactly where it belongs.
As metabolic health becomes one of the most important conversations in modern medicine, accurate terminology is more than a linguistic update—it’s a clinical tool that improves outcomes.
