NAFLD / MASLD Global Prevalence and Trends

What Is MASLD and How Does the Rename Affect Prevalence Numbers?

The term MASLD replaced NAFLD in June 2023 after a multi-society Delphi consensus involving the American Association for the Study of Liver Diseases (AASLD), the European Association for the Study of the Liver (EASL), and several other major liver societies. The older "nonalcoholic" framing was considered stigmatizing and mechanistically imprecise, so the field aligned on "metabolic dysfunction-associated steatotic liver disease." Diagnostic criteria shifted slightly: MASLD now requires hepatic steatosis plus at least one of five cardiometabolic risk factors (overweight or obesity, hyperglycemia, hypertension, elevated triglycerides, or low HDL cholesterol) rather than simple alcohol exclusion.

A 2023 systematic review published in The Lancet Gastroenterology and Hepatology estimated that approximately 38.2% of the global adult population meets MASLD criteria, compared with 29.8% under the older NAFLD definition applied to the same datasets. [1] The difference reflects the positive cardiometabolic criterion: most people who had NAFLD also have at least one metabolic risk factor, so the MASLD umbrella captures a slightly larger group while adding clinical specificity.

Why the Definition Change Matters Epidemiologically

Under NAFLD, diagnosis required excluding alcohol use above a threshold (typically more than 21 drinks per week for men, more than 14 for women). That exclusion criterion made population-level comparisons difficult because alcohol thresholds varied by study and country. MASLD shifts the anchor to what the liver is actually doing metabolically, which makes cross-national prevalence estimates more comparable going forward.

The 2023 consensus document notes: "The term NAFLD is replaced by MASLD to reflect the central role of metabolic dysfunction and to reduce stigma associated with the term 'nonalcoholic.'" [2] Clinicians using ICD-10 codes should note that the transition to updated coding is still underway in many health systems.

Steatotic Liver Disease as an Umbrella

The broader category is now called steatotic liver disease (SLD). Within SLD, MASLD is the largest subtype. MetALD (a new subcategory) covers people who meet MASLD criteria but also drink more than the MASLD alcohol threshold. Pure alcohol-related liver disease and other specific causes (drug-induced, genetic) sit in separate SLD subgroups. This taxonomy matters for prevalence counting because earlier NAFLD studies excluded people with any significant alcohol use, potentially undercounting metabolic fatty liver in heavy drinkers.

Global Prevalence Figures: Region by Region

Prevalence is not uniform across the globe. A landmark 2022 meta-analysis by Younossi et al. Published in the Journal of Hepatology (N = 1,201 studies, covering 245 million individuals) estimated NAFLD prevalence at 29.8% globally under older criteria, with significant regional variation. [3] Applying 2023 MASLD criteria raises most of these regional figures by roughly 5 to 8 percentage points.

Middle East and Latin America: Highest Burden

The Middle East carries the highest regional burden: prevalence studies consistently place MASLD above 40% in Gulf Cooperation Council countries. Saudi Arabia, for example, reported NAFLD prevalence of 33.9% in community studies before the rename, suggesting MASLD prevalence likely exceeds 40% under updated criteria. Latin American countries, particularly Mexico, Argentina, and Colombia, show similar patterns, driven by high rates of obesity and type 2 diabetes combined with genetic susceptibility variants in the PNPLA3 gene (rs738409).

Asia: High Prevalence Despite Lower BMI

Asia presents a paradox. Despite lower average body mass index values compared with Western populations, MASLD prevalence in East and South Asia ranges from 27% to 37% in recent studies. [3] The PNPLA3 and TM6SF2 risk alleles are more common in East Asian populations, and visceral fat accumulation occurs at lower BMI thresholds, explaining why a person with BMI <27 may still have significant hepatic steatosis. China alone accounts for an estimated 250 million MASLD cases, making it the country with the largest absolute number of affected individuals.

Europe and North America

European prevalence sits around 30 to 35% in population-based imaging studies, with Southern European countries (Italy, Spain) reporting higher rates than Northern Europe. The United States shows a prevalence of roughly 32 to 40% depending on the diagnostic method used (ultrasound, controlled attenuation parameter, or liver biopsy). Hispanic Americans carry the highest ethnic-group prevalence in the US at approximately 45%, largely attributed to higher frequency of the PNPLA3 I148M allele. [4]

Sub-Saharan Africa: Underdiagnosed, Emerging

Sub-Saharan African data remain sparse. Available studies suggest community prevalence between 13% and 20%, but access to ultrasound and controlled attenuation parameter (CAP) technology for population screening is limited. As urbanization accelerates dietary change and physical inactivity, African prevalence is expected to rise faster than any other region through 2040.

Temporal Trends: How Quickly Is MASLD Spreading?

MASLD prevalence has roughly doubled over the past 30 years. In 1991, population-level ultrasound studies in Western Europe placed NAFLD prevalence around 14 to 16%. By 2016, a pooled analysis estimated global NAFLD prevalence at 25.2% (95% CI: 22.1-28.6%). [5] The 2022 Younossi meta-analysis showed 29.8%, and the 2023 MASLD-criteria estimate stands at 38.2%. This is not merely a diagnostic artifact: liver biopsy series and imaging cohorts both confirm rising rates of histologic steatosis independent of changing diagnostic thresholds.

The Obesity-Diabetes Engine

The parallel rise in obesity and type 2 diabetes drives most of this trend. The global age-standardized obesity prevalence roughly tripled between 1975 and 2016 according to a New England Journal of Medicine analysis of 195 countries (N = 68.5 million participants). [6] MASLD risk increases sharply with BMI: the odds ratio for MASLD is approximately 3.5 for individuals with obesity compared with those of normal weight. Type 2 diabetes adds independent risk, with MASLD prevalence reaching 55 to 70% in patients with established T2D. [3]

Pediatric Trends: A Particularly Concerning Signal

Children are not exempt. A 2021 meta-analysis in JAMA Pediatrics estimated NAFLD prevalence at 7.6% in the general pediatric population, rising to 34.2% in children with obesity. [7] Because fatty liver in childhood predicts adult cirrhosis and cardiovascular disease decades earlier than adult-onset disease, pediatric MASLD represents a coming wave of end-stage liver disease. No pharmacological therapy is FDA-approved for pediatric MASLD as of mid-2025; lifestyle modification remains the primary intervention.

Disease Spectrum and Progression Risk

MASLD itself is a histologic continuum. Simple steatosis (fat only, no significant inflammation) carries a relatively low short-term progression risk. Non-alcoholic steatohepatitis (NASH), or metabolic dysfunction-associated steatohepatitis (MASH) under the new naming convention, adds lobular inflammation and hepatocyte ballooning and carries a fibrosis progression rate of approximately 1 fibrosis stage per 7 years. [8]

MASH-to-Cirrhosis Progression

A modeling study using Global Burden of Disease data projected that NASH-related cirrhosis cases would increase by 55.7% between 2016 and 2030 in the United States alone. [9] Globally, MASLD is already the second-leading indication for liver transplant listing in the United States and is on track to become the leading indication by 2030.

Cardiovascular Risk Dominates Mortality

Despite the liver being the defining organ, cardiovascular disease is the leading cause of death in MASLD patients, not liver failure. A meta-analysis covering 34,000 MASLD patients found a cardiovascular mortality hazard ratio of 1.55 (95% CI: 1.13-2.13) compared with matched controls without MASLD. [10] This shapes clinical management: treating MASLD is inseparable from treating dyslipidemia, hypertension, and insulin resistance.

Key Risk Factors Driving the Global Burden

The table below organizes MASLD risk factors by modifiability, a framework the HealthRX medical team uses to prioritize clinical counseling and identify intervention targets.

| Risk Factor | Prevalence in MASLD Patients | Modifiable? | |---|---|---| | Overweight or obesity (BMI 25-29.9 / >30) | 51-80% | Yes | | Type 2 diabetes or prediabetes | 40-70% | Partially | | Hypertriglyceridemia | 40-56% | Yes | | Hypertension | 39-68% | Yes | | Low HDL cholesterol | 30-42% | Yes | | PNPLA3 I148M variant (rs738409) | 30-48% | No | | Hypothyroidism | 15-25% | Yes | | Polycystic ovary syndrome (PCOS) | 15-55% (in women with PCOS) | Partially | | Sleep apnea | 15-49% | Yes |

Genetic risk, particularly the PNPLA3 I148M variant, modifies severity more than it drives prevalence at the population level. Most of the global burden increase is attributable to modifiable metabolic factors. [4]

Diet and Physical Inactivity

Ultra-processed food consumption, high fructose intake (especially from sugar-sweetened beverages), and sedentary behavior are the most population-attributable dietary drivers. A 2020 study in Gut found that each additional daily serving of sugar-sweetened beverages was associated with a 16% higher odds of MASLD (OR 1.16, 95% CI: 1.08-1.25). [11] Physical inactivity independently raises hepatic fat content even after controlling for BMI, because skeletal muscle is a major sink for circulating lipids that would otherwise deposit in the liver.

Medications and Secondary Causes

Several common medications raise hepatic fat. Corticosteroids, tamoxifen, methotrexate, amiodarone, and certain antiretrovirals (particularly stavudine and zidovudine) can cause drug-induced steatosis that mimics MASLD histologically. Clinicians should document full medication lists before attributing steatosis to metabolic causes alone.

Screening, Diagnosis, and Guideline Positions

No major society currently recommends universal population screening for MASLD. The AASLD 2023 practice guidance states that clinicians should evaluate for MASLD in patients with obesity, type 2 diabetes, or metabolic syndrome, and should use non-invasive tests (NITs) to stratify fibrosis risk before considering liver biopsy. [2]

Non-Invasive Fibrosis Tests

The FIB-4 index (calculated from age, ALT, AST, and platelet count) is the recommended first-line NIT. A FIB-4 below 1.30 has a negative predictive value of approximately 90% for advanced fibrosis in most MASLD cohorts. Scores above 2.67 warrant further evaluation with liver stiffness measurement (LSM) by vibration-controlled transient elastography (FibroScan) or MR elastography. [2]

The 2024 FDA Approval: Resmetirom

In March 2024, the FDA approved resmetirom (Rezdiffra, Madrigal Pharmaceuticals) as the first drug specifically indicated for MASH with moderate-to-advanced fibrosis (F2-F3) in adults. [12] The approval was based on the MAESTRO-NASH trial (N = 966), in which 25.9% of patients receiving resmetirom 100 mg daily achieved MASH resolution without fibrosis worsening at 52 weeks versus 9.7% on placebo (P<0.001). The drug is a thyroid hormone receptor-beta agonist that reduces hepatic lipid synthesis and promotes mitochondrial fatty acid oxidation. Approval does not cover F0-F1 or cirrhosis (F4).

GLP-1 Receptor Agonists and Emerging Data

Semaglutide 2.4 mg weekly (Wegovy) showed MASH resolution in 59% of patients versus 17% on placebo in a phase 2 trial (N = 320, 72 weeks). [13] Phase 3 ESSENCE trial results are expected in 2025. Tirzepatide (Mounjaro/Zepbound), a dual GIP/GLP-1 receptor agonist, also reduced hepatic fat fraction significantly in the SURMOUNT-1 subgroup analysis. These agents do not yet carry an FDA indication specifically for MASH but are used off-label in clinical practice for metabolic risk reduction when obesity or T2D coexist.

Socioeconomic and Demographic Dimensions

MASLD burden is not distributed randomly across income levels or demographics. Lower socioeconomic status associates with higher MASLD prevalence in high-income countries, mediated through diet quality, food environment, physical inactivity, and stress-related cortisol dysregulation. A study using NHANES data (N = 11,154) found that adults in the lowest income quintile had a 32% higher odds of NAFLD compared with the highest quintile after adjusting for BMI and diabetes. [14]

Sex also plays a role. Men develop MASLD at lower BMI thresholds and younger ages, but post-menopausal women show accelerated fibrosis progression, likely due to loss of estrogen's hepatoprotective effects. Women with PCOS carry a particularly elevated risk: prevalence of MASLD in PCOS reaches 55% in some clinic-based series. [15]

Economic Burden

MASLD costs healthcare systems substantially. A 2017 economic modeling study estimated the annual US burden of NAFLD at $103 billion, accounting for direct medical costs plus lost productivity. [16] Globally, the figure likely exceeds $300 billion annually when disability-adjusted life-years lost to MASH-related cirrhosis and hepatocellular carcinoma are monetized. Resmetirom at list price (approximately $47,400 per year) will increase pharmacy costs substantially, making cost-effectiveness analyses for targeted treatment of high-risk MASLD patients an active area of policy discussion.

The Path Forward: What Declining Trend Scenarios Would Require

Reversing or even stabilizing global MASLD prevalence requires population-level reductions in obesity and T2D. The GLP-1 receptor agonist class offers the first pharmacological tool capable of achieving 10 to 20% body weight loss at scale. If semaglutide or tirzepatide penetrate 15% of eligible obese adults over the next decade, modeling suggests MASLD prevalence could stabilize rather than continue its current upward trajectory. That scenario depends heavily on access, cost, and long-term adherence data not yet available from real-world cohorts. Structural interventions including sugar taxes, food labeling reform, and urban planning for physical activity remain the most cost-effective tools at population scale according to WHO modeling. [17]

Pediatric intervention is the highest-use window. A 10% reduction in childhood obesity rates, maintained into adulthood, could prevent an estimated 5 million MASH-cirrhosis cases globally by 2050 based on current projection models.

Clinicians managing adults with type 2 diabetes should screen for advanced fibrosis using FIB-4 at least once, as recommended by AASLD 2023 guidance, because detecting F2-F3 fibrosis now opens a specific pharmacological treatment pathway with resmetirom. [2]