What is fatty liver disease?

Fatty liver disease occurs when excess fat (more than 5–10% of the liver's weight) accumulates in liver cells. It affects approximately 30% of European adults. There are two main types: alcoholic fatty liver disease (AFLD) caused by excessive alcohol intake, and non-alcoholic fatty liver disease (NAFLD) linked to metabolic factors like obesity and insulin resistance.

What are the first signs of fatty liver disease?

Early-stage fatty liver disease is often completely asymptomatic. When symptoms do appear, they typically include persistent fatigue, mild discomfort in the upper right abdomen, and occasional appetite loss. Most cases are discovered through blood tests or imaging ordered for other reasons.

Can fatty liver disease be reversed?

Yes, particularly in early stages. Simple steatosis and early steatohepatitis are largely reversible through lifestyle changes, before significant scarring (fibrosis) has developed. A weight loss of 7–10%, 150 minutes of weekly exercise, and a balanced, low-glycemic diet significantly reduce liver fat and support regeneration.

Liver fat fraction (%PDFF)

Liver

Proton Density Fat Fraction measurement of the liver, quantifying hepatic fat content.

Also known as: proton density fat fraction, PDFF, liver fat percentage, hepatic steatosis MRI

Elevated values indicate hepatic steatosis (fatty liver), which may progress to more severe liver disease.

Reference range

Reference range
Level	Range
Intermediate	above 5 %
Normal	below 5 %

Source: Ahead Health benchmark

* Reference ranges may vary between labs and assays. Discuss your results with your doctor.

Why this matters

Elevated liver fat indicates fatty liver disease. This condition often develops silently, increasing risk for diabetes, cardiovascular disease, and progressive liver damage. Advanced stages can lead to fibrosis or cirrhosis with symptoms such as jaundice, swelling, and confusion. Because liver fat is strongly influenced by body weight, diet, physical activity, and alcohol intake, early detection is valuable since lifestyle changes can often reverse fatty liver before permanent damage occurs.

How this connects to other biomarkers

Liver fat fraction (PDFF) > 5% defines fatty liver (steatosis); > 15% is moderate, > 25% severe.
Elevated PDFF with elevated Alanine Aminotransferase (ALAT), central obesity, and high HOMA-Index confirms metabolic-associated fatty liver disease (MASLD, formerly called NAFLD).
Progressing liver scarring (fibrosis) is signaled by rising Fibrose-Score (FIB-4) and falling Albumin — PDFF measures fat, not scarring.

How often should I test Liver fat fraction (%PDFF)?

No guideline sets a fixed interval for measuring liver fat in people without known liver disease. A normal result, up to 5 percent, needs no extra check before your next MRI. If it is above 5 percent and you are actively working on lowering it, a repeat measurement every 3 to 6 months shows your progress. How often depends on your starting value.

Routine / screening: No fixed interval for people without known liver disease

When monitoring an intervention or change: Every 3 to 6 months while you are actively working on lowering a result above 5 percent, depending on your starting value

Note: Liver fat responds within weeks to weight loss or weight gain, so read a result together with any recent change in your weight. A difference of up to about 3 percentage points between two scans can be measurement variation rather than a real change.

Frequently asked questions

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