The Complete Guide to Fatty Liver (MASLD)
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It used to be called NAFLD. In 2023, researchers renamed it MASLD to reflect something important: this condition is a metabolic disease that shows up in the liver, not an isolated liver problem. Here's what changed and why it matters.
By Charles Kirkland, Founder, Metabolic Clarity Labs
Updated August 2026
Quick answer: MASLD (Metabolic dysfunction-Associated Steatotic Liver Disease) is fat buildup in the liver that occurs alongside at least one cardiometabolic risk factor, such as excess weight, elevated blood sugar, high blood pressure, high triglycerides, or low HDL. It replaced the older term NAFLD in 2023. It's diagnosed through blood tests, imaging, and sometimes biopsy, and its progressive form, MASH, now has an FDA-approved treatment option for some patients as of 2024, though lifestyle changes remain the foundation of management.
Why the name changed in 2023
For years this condition was called non-alcoholic fatty liver disease, or NAFLD, a name defined by what it wasn't rather than what it was. In 2023, a multi-society consensus process involving liver specialty organizations renamed it metabolic dysfunction-associated steatotic liver disease, or MASLD.
The new name reflects a shift in understanding: this condition is now understood as a hepatic manifestation of metabolic dysfunction, closely tied to insulin resistance, obesity, and the same patterns behind metabolic syndrome, rather than a liver problem defined mainly by the absence of heavy alcohol use.
How MASLD is diagnosed
The current diagnostic approach requires two things: evidence of fat accumulation in the liver (steatosis), plus at least one cardiometabolic risk factor. Those risk factors include:
- Elevated BMI or waist circumference
- Fasting glucose at or above 100 mg/dL, or type 2 diabetes
- Blood pressure at or above 130/85 mmHg, or on blood pressure medication
- Triglycerides at or above 150 mg/dL, or on lipid-lowering medication
- Low HDL cholesterol
Notice that these are the same five criteria used to evaluate metabolic syndrome. That overlap isn't a coincidence, it's the entire reason for the name change.
People with steatotic liver disease and significant alcohol intake are now classified separately, under a category called MetALD, which sits between MASLD and alcohol-related liver disease.
How fat in the liver is actually detected
Liver enzymes like ALT and AST are often checked first, but they have an important limitation: they can be completely normal even when significant fat has accumulated in the liver. Enzyme elevation tends to reflect active liver cell injury, not simply the presence of fat, which is why normal blood work doesn't rule out MASLD.
Imaging is typically more informative. A standard abdominal ultrasound can detect fat in the liver, and specialized elastography techniques, sometimes called FibroScan, can estimate both fat content and the degree of liver stiffness, which relates to scarring. In some cases, particularly when fibrosis is suspected, a liver biopsy remains the most definitive test.
From MASLD to MASH: understanding the progression
Not everyone with fat in their liver develops ongoing liver damage. A portion of people with MASLD progress to a more serious form called metabolic dysfunction-associated steatohepatitis, or MASH, which involves active inflammation and cell injury on top of the fat accumulation. Over years, MASH can progress to fibrosis, and in a smaller subset of cases, to cirrhosis.
This is why monitoring matters. Simple fatty liver without inflammation carries a different risk profile than MASH with fibrosis, and the two require different levels of follow-up.
Treatment: lifestyle first, with a newer medication option
For most people with MASLD, the foundation of management remains the same: a sustained 7 to 10 percent reduction in body weight has been shown in research to meaningfully reduce liver fat and, in some cases, improve inflammation and early fibrosis. This typically involves a combination of dietary changes, increased physical activity, and management of related conditions like diabetes and high triglycerides.
In March 2024, the FDA approved resmetirom, the first medication specifically approved for adults with MASH and moderate to advanced liver fibrosis, to be used alongside diet and exercise. It is not appropriate for everyone with MASLD and requires a physician to determine candidacy, monitor liver function, and manage treatment. It does not replace lifestyle changes.
Why we treat this as connected, not isolated
MASLD sits at the intersection of Glucose Load, Storage Load, and Inflammatory Load in our framework. Insulin resistance drives fat storage in the liver, that stored fat can worsen insulin resistance further, and the resulting inflammation can affect blood vessels and other organs beyond the liver itself. Treating fatty liver as an isolated organ problem misses why it developed in the first place.
What to ask your healthcare professional
Given my weight, blood sugar, and lipid panel, am I a candidate for fatty liver screening?
Would an ultrasound or elastography be useful for me even if my liver enzymes are normal?
If I'm diagnosed with MASLD, what weight loss target and timeline make sense for me?
How often should my liver markers be rechecked given my overall metabolic picture?
Frequently asked questions
Can fatty liver be found with normal liver enzyme tests?
Yes. Liver enzymes can be within normal range even when significant fat has accumulated, since enzymes primarily reflect active cell injury rather than fat content alone. Imaging is more reliable for initial detection.
Is fatty liver caused by drinking alcohol?
MASLD is specifically defined by the presence of cardiometabolic risk factors, separate from significant alcohol use. People with both heavy alcohol intake and steatotic liver disease are classified under a related but distinct category called MetALD.
Can fatty liver improve with weight loss?
Research shows that a sustained 7 to 10 percent reduction in body weight is associated with meaningful improvement in liver fat and, in many cases, early inflammation. Results vary by individual and by how much fibrosis, if any, is already present.
Does everyone with obesity have fatty liver?
No. While obesity is a major risk factor, MASLD can also occur in people at a normal weight, sometimes called lean MASLD, and not everyone with obesity develops significant liver fat.
The Metabolic Clarity takeaway
MASLD's 2023 renaming wasn't just a label change. It reflected what the research already showed: this is a metabolic condition that happens to show up in the liver, sharing the same five risk factors as metabolic syndrome.
Next step: If your waist circumference, blood sugar, blood pressure, or lipids are outside a healthy range, the metabolic syndrome guide explains how these markers connect, including to liver health.
Sources
- American Association for the Study of Liver Diseases, MASLD Practice Guidance
- NIH National Institute of Diabetes and Digestive and Kidney Diseases, MASLD and MASH
- FDA, FDA Approves First Treatment for Patients with Liver Scarring Due to Fatty Liver Disease
- EASL-EASD-EASO Clinical Practice Guidelines on MASLD Management
Charles Kirkland is the founder of Metabolic Clarity Labs. He is not a physician. His writing is based on his own documented health experience, alongside cited research sources.
Medical and regulatory disclaimer: This article is for general education only. It does not diagnose, treat, or prevent disease and does not replace advice from a physician or other qualified health professional. Fatty liver disease requires proper medical evaluation; do not attempt to self-diagnose or self-treat based on this article.
