What Is MASLD (NAFLD)? The Most Common Liver Disease You’ve Never Heard Of

One in four adults in North America has it. Most have no symptoms. Most have never been diagnosed. Most would be surprised to learn they’re in this category, because MASLD is a disease associated in popular imagination with alcoholics and the morbidly obese — and most people with it are neither.

If you’ve had bloodwork showing elevated liver enzymes and your doctor mentioned “fatty liver,” or if you have metabolic risk factors (extra weight around the midsection, high triglycerides, type 2 diabetes, insulin resistance), this article is directly relevant to you.

This article is for educational purposes. It does not constitute medical advice. If you have elevated liver enzymes or suspect liver disease, consult a physician for proper diagnosis.

The Name Just Changed — Here’s Why

If you’ve been researching this topic, you may have seen both NAFLD and MASLD used interchangeably. They refer to the same condition, but the name changed in 2023 for important reasons.

NAFLD — Non-Alcoholic Fatty Liver Disease — was the terminology used from the 1980s through 2022. The “non-alcoholic” framing was intended to distinguish it from alcohol-related liver disease, but it caused problems:

It defined the disease by what it isn’t rather than what it is
It carried a mild stigma — “you don’t drink, so how did you get liver disease?”
It missed the real driver: metabolic dysfunction

MASLD — Metabolic-Associated Steatotic Liver Disease — adopted by a global consensus of hepatology societies in 2023. “Steatotic” means fat-accumulating. “Metabolic-associated” correctly names the actual cause: metabolic dysfunction — insulin resistance, elevated triglycerides, high blood sugar, abdominal obesity.

When you see “NAFLD” in older articles and studies, it means the same condition as MASLD. The biology didn’t change; the name did.

Prevalence: This Is Not a Rare Disease

Global: ~25–30% of adults worldwide — approximately 1.5–2 billion people North America: ~24–32% of adults, higher in people with obesity or type 2 diabetes Canada specifically: Studies estimate 20–30% prevalence in the general adult population

For context: MASLD is more common than type 2 diabetes (10–12% of adults) and far more common than most people assume when they think “liver disease.”

The prevalence has increased substantially over the past 30 years, tracking closely with increases in obesity, sedentary behavior, and processed food consumption. It is now the most common cause of chronic liver disease in Western countries and the fastest-growing indication for liver transplantation.

You Don’t Have to Drink to Have MASLD

This is the single most important thing to understand about MASLD: alcohol is not a cause or a risk factor. The defining criterion for MASLD is that significant alcohol consumption is absent (though mild-to-moderate drinking can coexist with MASLD).

The actual causes are metabolic:

Insulin resistance / type 2 diabetes — the strongest risk factor. Insulin resistance causes the liver to accumulate fat through increased de novo lipogenesis (fat synthesis) and impaired fat export
Central obesity — abdominal fat (visceral adipose tissue) releases inflammatory fatty acids directly into the portal circulation, driving hepatic fat accumulation
Hypertriglyceridemia — elevated blood triglycerides correlate strongly with hepatic steatosis
Metabolic syndrome — the cluster of central obesity + elevated blood pressure + elevated blood sugar + high triglycerides + low HDL. Having three of the five criteria constitutes metabolic syndrome; MASLD prevalence in metabolic syndrome is 50–70%
Diet — high fructose intake (particularly from sweetened beverages) is specifically implicated in hepatic fat accumulation through effects on hepatic de novo lipogenesis
Sedentary lifestyle — physical inactivity independently predicts MASLD beyond its contribution to obesity
Genetics — variants in PNPLA3, TM6SF2, and MBOAT7 genes increase MASLD risk and severity regardless of metabolic risk factors

Who gets MASLD: Not just overweight people. MASLD is present in approximately 7–20% of people with normal BMI — a phenomenon called “lean MASLD.” This is more common in people of Asian ancestry, who have higher visceral fat percentage at lower absolute weight. If you’re at a healthy weight but carry metabolic risk factors, you can still have MASLD.

The Progression: Steatosis to Cirrhosis

MASLD is a spectrum, not a single condition. Most people who have it will remain at the mildest stage and never progress. A significant minority will progress, and the downstream consequences are serious.

Stage 1: Hepatic Steatosis (Simple Fatty Liver) Fat accumulates in liver cells (hepatocytes) — defined as fat in >5% of liver cells on biopsy or by imaging. At this stage, liver cells are fat-laden but not significantly inflamed or damaged. This stage is largely reversible with lifestyle intervention. No symptoms. Normal or mildly elevated liver enzymes.

Approximately 80–85% of people with MASLD stay at this stage or improve.

Stage 2: MASH (Metabolic-Associated Steatohepatitis) Previously called NASH (Non-Alcoholic Steatohepatitis). Inflammation develops in the liver in addition to fat accumulation. Liver cells show characteristic “ballooning” (cellular stress). Moderate liver enzyme elevation. Still no distinctive symptoms. 15–20% of MASLD patients progress to this stage.

MASH is the stage at which fibrosis (scarring) can begin and the risk of serious outcomes increases significantly.

Stage 3: Liver Fibrosis Repeated inflammatory injury triggers the liver’s healing response — collagen deposition. Initially reversible (Stage F1-F2), progressing to more extensive scarring (Stage F3). Liver stiffness measurable on FibroScan begins to rise above normal. Still usually asymptomatic.

Stage 4: Cirrhosis (Stage F4) Extensive, largely irreversible scarring that distorts normal liver architecture. Portal hypertension develops — elevated pressure in the portal vein causing esophageal varices, ascites (fluid in the abdomen), splenomegaly. Liver enzymes may paradoxically normalize as functioning liver tissue is replaced by scar tissue.

Cirrhosis is not reversible with current treatments; management focuses on preventing complications.

Stage 5: Hepatocellular Carcinoma (HCC) Liver cancer developing on a background of cirrhosis. MASLD-related HCC is now the fastest-growing cause of liver cancer in Western countries. Risk is approximately 1–2% per year in patients with MASLD cirrhosis.

Why Most People Have No Idea They Have It

MASLD is called a “silent disease” for good reason. Through stages 1–3 — which can span years or decades — there are essentially no symptoms. The liver has remarkable functional reserve; you can lose 50–60% of liver function before symptoms appear.

When symptoms do eventually appear (typically late-stage): fatigue, right upper quadrant discomfort or fullness, and the symptoms of cirrhosis complications.

How it’s diagnosed:

Elevated liver enzymes (ALT, GGT, AST) on routine bloodwork — the most common way MASLD is discovered. But note: normal liver enzymes don’t rule out early MASLD; 30–50% of people with simple steatosis have normal enzyme levels.
Liver ultrasound — can detect hepatic steatosis (bright “echogenic” liver appearance) but misses mild steatosis and can’t stage fibrosis
FibroScan (transient elastography) — non-invasive measurement of liver stiffness; current standard for staging fibrosis without biopsy
Liver biopsy — the definitive diagnostic tool but invasive; not used routinely unless advanced disease is suspected

→ Liver Enzymes Explained: ALT, GGT, and AST Normal Ranges →

What Currently Works for MASLD

The good news: MASLD is often reversible, particularly in the early stages. The primary interventions are lifestyle-based.

Weight loss: 5–7% body weight reduction reduces hepatic steatosis. 7–10% reduction reduces MASH activity. 10% or more sustained weight loss can reverse fibrosis in some patients. This is the single most effective intervention.

Exercise: Independent of weight loss, aerobic exercise reduces liver fat content and improves metabolic parameters. Both aerobic and resistance training show benefit.

Diet: Reducing refined carbohydrates and fructose, increasing Mediterranean diet adherence, and reducing processed food intake all show benefit in prospective studies.

Pharmacotherapy: As of 2026, there are no FDA-approved pharmaceuticals specifically for MASLD at stage 1–2. Resmetirom received FDA approval in 2024 for MASH with liver fibrosis (Stage F2–F3) — the first approved MASH-specific drug. Several others are in Phase 3 trials. Tirzepatide and semaglutide (GLP-1 agonists) show significant MASLD benefit as secondary outcomes in their obesity trials.

Supplements: The January 2026 Annals of Gastroenterology RCT — 55 MASLD patients, 12 months, double-blind, placebo-controlled — found that DHM 300mg/day (combined with vitamins C, E, and choline) produced significant reduction in liver enzymes (ALT, GGT) and liver stiffness (6.3 → 5.3 kPa, p=0.001). This is the most rigorous human study of any supplement for MASLD to date.

Milk thistle (silymarin) has the most extensive evidence base in the supplement category — multiple meta-analyses demonstrate liver enzyme reduction in MASLD populations, though the effect size is more modest than the DHM 2026 trial result.

→ DHM Liver Health Study: 2026 RCT → → Liver Health Supplements: What Actually Works →

Practical Takeaway

If you have any of these: elevated liver enzymes on bloodwork, central obesity, type 2 diabetes, metabolic syndrome, high triglycerides, or family history of liver disease — MASLD is worth discussing with your doctor. A simple ALT and GGT blood test and an ultrasound can provide substantial information with minimal cost and no invasive testing.

If you’ve already been told you have “fatty liver” or elevated enzymes and you’re not in active medical management:

Weight loss through diet and exercise is the primary intervention — nothing else has comparable evidence for stage 1–2 MASLD
Reducing processed foods and refined carbohydrates specifically (not just calories) has evidence
Supplements with the best evidence: DHM (2026 RCT), milk thistle (multiple meta-analyses), and the combination stack that includes L-Cysteine, B vitamins, and antioxidants

MASLD at stages 1–2 is very treatable. The problem is that most people never know they have it.