Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

Definition & Nomenclature

In 2023, major liver societies agreed to retire the term “nonalcoholic fatty liver disease (NAFLD)” and replace it with metabolic dysfunction-associated steatotic liver disease (MASLD). Steatotic liver disease (SLD) is now used as the umbrella term for all causes of hepatic steatosis, including MASLD, alcohol-related and other specific etiologies.^[1][2]

MASLD describes patients who have:

• Evidence of hepatic steatosis (on imaging, noninvasive tests, or biopsy), and
• At least one cardiometabolic risk factor (e.g., obesity, type 2 diabetes, hypertension, dyslipidemia, or metabolic syndrome).

The inflammatory form of the disease—previously called nonalcoholic steatohepatitis (NASH)—is now called MASH (metabolic dysfunction-associated steatohepatitis) and is defined by steatosis plus necroinflammatory injury with hepatocyte ballooning and varying degrees of fibrosis.^[4]

Who Is At Risk? Key Cardiometabolic Factors

MASLD is tightly linked to cardiometabolic risk. It is most common in people with:

• Overweight or obesity (especially central/visceral adiposity)
• Type 2 diabetes or prediabetes
• Hypertension and atherosclerotic cardiovascular disease
• Dyslipidemia (high triglycerides, low HDL, high non-HDL cholesterol)
• Metabolic syndrome or insulin resistance

MASLD has become the most common chronic liver disease worldwide, paralleling global rises in obesity and diabetes, and is now a leading cause of cirrhosis, hepatocellular carcinoma (HCC), and liver transplantation in many regions.^[5][6]

Steatosis (fat accumulation) within hepatocytes is the core histologic feature of MASLD. Educational histology image via Wikimedia Commons.^[3]

Important points for transplant patients and candidates:

• MASLD often coexists with other liver diseases (e.g., viral hepatitis, autoimmune liver disease) and can accelerate fibrosis.
• Cardiovascular disease is a major cause of morbidity and mortality in MASLD, often exceeding liver-related events.
• Optimizing cardiometabolic health (weight, glycemic control, lipids, blood pressure) is central to MASLD management.

Symptoms & Who Should Be Screened

Many people with MASLD feel completely well and are diagnosed incidentally when:

• Liver enzymes are mildly elevated on routine blood work, or
• Imaging (ultrasound, CT, MRI) done for another reason shows a “bright” or fatty liver.

When symptoms do occur, they are often nonspecific:

• Fatigue and low energy
• Dull right upper quadrant discomfort
• General malaise

Patients usually do not develop specific “liver failure” symptoms until advanced fibrosis or cirrhosis appears, with findings such as ascites, leg edema, jaundice, encephalopathy, or variceal bleeding.^[3][7]

Who deserves targeted screening? Consensus guidelines recommend case-finding in individuals with:

• Type 2 diabetes (very high MASLD and MASH prevalence)
• Obesity or overweight with additional metabolic risk factors
• Unexplained increases in liver enzymes
• Radiologic evidence of steatosis
• Strong family history of MASLD, cirrhosis, or cardiometabolic disease

For these groups, noninvasive fibrosis assessment (e.g., FIB-4, NAFLD fibrosis score, elastography) is recommended to identify people at risk for advanced fibrosis who need hepatology referral and closer follow-up.^[5][8]

Diagnosis & Noninvasive Assessment

The diagnostic evaluation aims to:

• Confirm steatosis
• Determine whether metabolic risk factors are present (supporting MASLD)
• Exclude competing causes of steatosis (e.g., significant alcohol, medications, viral hepatitis, rare genetic/metabolic conditions)
• Assess fibrosis stage and identify patients with advanced disease

Common components include:^[3][7][8]

• History & exam: detailed alcohol history, medications, metabolic risk factors, family history, signs of cirrhosis.
• Blood tests: liver enzymes, platelets, metabolic labs (glucose, A1c, lipids), viral hepatitis serologies, autoantibodies when indicated.
• Imaging: ultrasound (screening), CT or MRI, and increasingly MRI-PDFF for quantifying liver fat.
• Noninvasive fibrosis scores: FIB-4, NAFLD Fibrosis Score, ELF, or other validated algorithms.
• Elastography: vibration-controlled transient elastography (FibroScan) or MR elastography to estimate liver stiffness.
• Liver biopsy: reserved for diagnostic uncertainty, suspected alternative diagnoses, or when noninvasive tests are discordant and management hinges on staging.

Staging & Natural History Of MASLD

MASLD spans a spectrum:

• Simple steatosis (nonfibrotic MASLD): excess liver fat but no significant inflammation or fibrosis.
• MASH: steatosis plus inflammation, hepatocyte ballooning, and variable fibrosis.
• Advanced fibrosis (F3–F4): bridging fibrosis and cirrhosis.

The main driver of liver-related outcomes is fibrosis stage, not the degree of steatosis alone. Advanced fibrosis and cirrhosis are strongly associated with higher risks of decompensation, hepatocellular carcinoma, and need for liver transplantation.^[5][6]

However, many patients with MASLD die of cardiovascular disease before they develop cirrhosis. That is why comprehensive risk reduction (blood pressure, lipids, glycemic control, antiplatelet therapy when appropriate) is central to MASLD management.

For transplant candidates, MASLD can be:

• The primary indication for transplantation (cirrhosis ± HCC)
• A cofactor that worsens outcomes in other liver diseases
• A post-transplant issue, when weight gain, steroids, and metabolic complications cause recurrent steatosis in the graft

Treatment: Lifestyle, Weight Loss & Risk Factor Control

There is no single “magic pill” for MASLD, but there is strong evidence that lifestyle interventions and weight loss can reduce liver fat, improve inflammation, and even regress fibrosis, especially when weight loss reaches 7–10% of baseline body weight.^[7][9]

Cornerstones of therapy include:

• Weight loss: via calorie reduction, Mediterranean-style or DASH-style patterns, and reduction of sugar-sweetened beverages and ultra-processed foods.
• Physical activity: at least 150–300 minutes/week of moderate-intensity exercise, plus resistance training 2–3 times per week.
• Glycemic control: especially in type 2 diabetes, using agents that also benefit liver and cardiovascular risk (e.g., GLP-1 receptor agonists, SGLT2 inhibitors as appropriate).
• Lipid management: statins are safe in MASLD and should be used according to cardiovascular risk guidelines.
• Blood pressure control: following hypertension guidelines.
• Alcohol moderation: even though MASLD is defined in people without significant alcohol-related liver disease, additional alcohol can worsen steatosis and fibrosis.

Bariatric surgery and endoscopic metabolic procedures can be highly effective in carefully selected patients with obesity, leading to substantial, durable weight loss and improvements in steatosis, MASH, and fibrosis.^[5][9]

Medications, Clinical Trials & Transplant Considerations

Several pharmacologic agents are being studied or used off-label to treat MASH and advanced MASLD, often in conjunction with lifestyle changes. These include:

• Insulin sensitizers (e.g., pioglitazone in some non-cirrhotic patients with biopsy-proven NASH/MASH)
• GLP-1 receptor agonists and dual/triple agonists that support weight loss and cardiometabolic risk reduction
• Emerging agents targeting fibrosis, inflammation, bile acid pathways, or lipid metabolism

As of 2025, guidelines emphasize that drugs should be targeted to patients at greatest risk (significant fibrosis or MASH) and that therapies are best delivered in combination with aggressive lifestyle and cardiometabolic care.^[5][8]

Transplant implications:

• MASLD/MASH is now a leading cause of cirrhosis and a major indication for liver transplantation in many countries.
• Transplant evaluation must carefully assess cardiovascular risk, diabetes, obesity, and sleep apnea.
• Post-transplant, the same metabolic drivers can recur, so ongoing weight and risk-factor management are critical.

Patient Story: “I Thought It Was Just My Weight”

Maria is a 56-year-old woman with long-standing type 2 diabetes, hypertension, and obesity. For years, she had mildly elevated liver enzymes that were brushed off as “fatty liver.” She felt tired, but she assumed it was her job and age.

When she changed primary care providers, her new doctor noticed that her platelet count was falling and ordered a liver ultrasound, which showed steatosis and a nodular contour suggestive of cirrhosis. Further evaluation with elastography confirmed advanced fibrosis. She was referred to hepatology, where she learned that her condition was now called MASLD, and that she likely had MASH with cirrhosis.

Her team created a plan: a structured weight-loss program, a GLP-1 receptor agonist to help her diabetes and weight, statin therapy for her cardiovascular risk, and close hepatology follow-up with HCC surveillance. With support, Maria lost 12% of her body weight over 18 months, improved her diabetes control, and stabilized her liver tests. She remains under careful surveillance, but she feels more in control—because she finally understands what MASLD is and what she can do about it.

References

1. AASLD. New MASLD Nomenclature (Fatty Liver Disease Terminology Changes). Official summary of the transition from NAFLD to MASLD and MASH, including definitions and rationale.
2. Multinational liver societies announce new fatty liver disease nomenclature. AASLD, 2023. Joint statement from international liver societies adopting MASLD/MASH terminology and criteria.
3. Wikimedia Commons. Fatty liver – educational images and diagrams. Source of illustrative images depicting steatosis and stages of liver damage used on this page.
4. AASLD Liver Fellow Network. “Steatotic-What? Changes in Fatty Liver Nomenclature.” Clinician-focused explanation of SLD, MASLD, MASH and related terms, with practical examples.
5. EASL–EASD–EASO Clinical Practice Guidelines on MASLD (2024). Comprehensive guidelines covering definitions, screening, diagnosis, noninvasive tests, and management of MASLD.
6. Chan WK et al. Metabolic Dysfunction–Associated Steatotic Liver Disease. Diabetes Care. 2025. Review of MASLD epidemiology, cardiometabolic links, and clinical implications in people with diabetes.
7. NIDDK. Nonalcoholic Fatty Liver Disease (NAFLD) & NASH – Symptoms, Causes, Diagnosis & Treatment. Patient-friendly overview of fatty liver disease, now aligned with MASLD/MASH terminology, including progression and complications.
8. Jin X et al. The new definition of metabolic dysfunction-associated steatotic liver disease. 2025. Detailed discussion of MASLD criteria, overlap with prior NAFLD definitions, and implications for practice and research.
9. NIDDK. Treatment for NAFLD & NASH (MASLD & MASH). Practical guidance on lifestyle interventions, weight loss, and risk-factor modification for patients with steatotic liver disease.
10. Mayo Clinic. Fatty liver disease (MASLD) – Symptoms and causes. Clinical description of MASLD, its risk factors, and progression, written for patients and families.