Hepatic steatosis is the medical term for a fatty liver. It means fat has built up inside your liver cells beyond what’s considered normal. Every liver contains some fat, but when fat makes up more than 5% to 10% of the liver’s total weight, it crosses the threshold into steatosis. You might see this term on an imaging report, a blood test follow-up, or a pathology result, and it’s one of the most common liver conditions worldwide.
How Fat Builds Up in the Liver
Your liver processes fats as part of its normal job. It pulls fatty acids from your bloodstream, packages them, and sends them out to other tissues for energy or storage. Problems start when the liver takes in more fat than it can export or burn off.
Two main pathways drive the excess. First, fat stored in your body’s fat tissue gets released into the bloodstream and absorbed by the liver. When you have insulin resistance, a hallmark of conditions like type 2 diabetes and obesity, your fat cells become less responsive to insulin’s signal to stop releasing fat. The result is a steady flood of fatty acids heading straight to the liver. Second, the liver itself can manufacture new fat from sugar in your blood, a process that ramps up when both insulin and blood sugar levels stay chronically high. Together, these two mechanisms overwhelm the liver’s ability to keep up, and fat droplets accumulate inside liver cells.
Why the Condition Often Has No Symptoms
Most people with hepatic steatosis feel completely fine. The condition rarely causes noticeable symptoms in its early stages, which is why it’s frequently discovered by accident during imaging for an unrelated issue or through routine blood work that shows mildly elevated liver enzymes. When symptoms do appear, they tend to be vague: a sense of fullness or dull discomfort in the upper right side of your abdomen, or persistent fatigue and weakness. A doctor may also notice an enlarged liver during a physical exam.
The absence of symptoms doesn’t mean the condition is harmless. Left unchecked, simple fat buildup can progress to inflammation of the liver (called steatohepatitis), which over years can lead to scarring (fibrosis) and eventually cirrhosis.
Grades of Liver Fat
Not all fatty livers are equally fatty. Doctors grade steatosis on a three-tier scale based on how much of the liver tissue is affected:
- Grade S1 (mild): Fat affects less than one-third of the liver, roughly 11% to 33% of liver cells.
- Grade S2 (moderate): Fat affects between one-third and two-thirds of the liver, or 34% to 66% of cells.
- Grade S3 (severe): Fat affects more than two-thirds of the liver, 67% or more.
These grades help your doctor track how the condition changes over time and determine how aggressively to approach treatment.
How It’s Diagnosed
The most common way hepatic steatosis is detected is through an abdominal ultrasound, which shows the liver appearing brighter than normal when fat is present. For a more precise measurement, many clinics use a specialized ultrasound device called a FibroScan. This test produces a CAP score (measured in decibels per meter) that estimates the amount of fat in your liver. A score below 238 dB/m is considered normal. Scores between 238 and 260 correspond to mild steatosis, 260 to 290 to moderate, and anything above 290 to severe. The test is painless, takes about 10 minutes, and doesn’t require any needles.
Blood tests can raise suspicion but can’t confirm steatosis on their own. Elevated liver enzymes, particularly ALT and AST, may prompt further imaging. In some cases, a liver biopsy is performed to check for inflammation or scarring that imaging can’t reliably detect.
Risk Factors and Who Gets It
Hepatic steatosis is closely tied to metabolic health. The three strongest risk factors are being overweight or obese, having type 2 diabetes, and having features of metabolic syndrome (high blood pressure, high triglycerides, low HDL cholesterol, elevated blood sugar, or a large waist circumference). Having even two of these metabolic markers alongside evidence of liver fat is enough for a diagnosis under current guidelines.
Alcohol is the other major contributor. Heavy or prolonged drinking causes fat to accumulate in the liver through a separate but overlapping pathway. In practice, many people have a mix of metabolic and alcohol-related factors, which is why the medical community recently introduced a new category called MetALD to describe the overlap.
Updated Medical Terminology
If you’ve seen the terms NAFLD or NASH before, those names are being phased out. In 2023, major liver disease organizations officially replaced “nonalcoholic fatty liver disease” (NAFLD) with “metabolic dysfunction-associated steatotic liver disease,” or MASLD. The inflammatory form, previously called NASH, is now MASH. The umbrella term covering all causes of liver fat is “steatotic liver disease” (SLD).
The change happened for two reasons. The old names defined the condition by what it wasn’t (nonalcoholic) rather than what it was, which made the terminology confusing and clinically imprecise. The word “fatty” was also considered stigmatizing. The new names focus on the actual metabolic drivers behind the disease: insulin resistance, obesity, and related conditions. If your doctor uses MASLD, they’re talking about the same condition as NAFLD, just with updated, more accurate language.
Treatment and Reversibility
The encouraging news about hepatic steatosis is that it’s reversible, especially in earlier stages. Losing as little as 3% to 5% of your total body weight can start clearing fat from your liver cells. For someone who weighs 200 pounds, that’s just 6 to 10 pounds. Greater weight loss brings greater benefit: losing 7% to 10% of body weight can reduce liver inflammation in people who have progressed to steatohepatitis.
There is no single diet proven superior for fatty liver, but reducing sugar intake, particularly from sugary drinks and refined carbohydrates, directly targets one of the main pathways feeding liver fat production. Regular physical activity helps independently of weight loss by improving how your body handles insulin and processes fat. Even moderate exercise like brisk walking several times a week makes a measurable difference.
For people who have already developed significant scarring, the FDA approved the first medication for liver fibrosis caused by fatty liver disease in 2024. The drug, resmetirom (sold as Rezdiffra), works by activating a thyroid hormone receptor in the liver that helps reduce fat accumulation. It’s approved for adults with moderate to advanced scarring who don’t yet have cirrhosis, and it’s meant to be used alongside diet and exercise rather than as a replacement for lifestyle changes.
What Progression Looks Like
Simple steatosis on its own carries a relatively low risk of serious liver damage. The danger point is when inflammation enters the picture. Roughly 20% to 30% of people with simple fatty liver go on to develop steatohepatitis, where fat accumulation triggers an immune response that damages liver cells. From there, repeated cycles of damage and repair can produce fibrosis, a buildup of scar tissue that gradually stiffens the liver and impairs its function.
Fibrosis progresses through four stages, with stage 4 being cirrhosis. The timeline varies widely. Some people live decades with stable, mild steatosis that never progresses. Others, particularly those with poorly controlled diabetes or ongoing heavy alcohol use, can develop significant fibrosis within a few years. Regular monitoring, whether through periodic blood work, imaging, or FibroScan, helps catch progression early when it’s still reversible or manageable.