Liver Fibrosis Stages F0 to F4: What Each Stage Means

TL;DR

• Liver fibrosis (scarring) is staged from F0 (none) through F1 (mild), F2 (significant), F3 (advanced, “bridging”) to F4 (cirrhosis). The stage is the best predictor of long-term outcomes in fatty liver, more than how much fat you have.
• Most people are staged without a biopsy: a FIB-4 score from routine blood work first, then a FibroScan or ELF blood test if needed. Biopsy is reserved for unclear or high-risk cases.
• Early stages can improve with sustained weight loss. Two medicines are approved for MASH with F2–F3 fibrosis, and cirrhosis needs specialist care.

Liver fibrosis is scarring, and doctors describe it in five stages from F0 to F4. F0 means no scarring, F2 is called significant, F3 is advanced (bridging) fibrosis, and F4 is cirrhosis. In fatty liver, this stage matters more than the amount of fat, because it’s the thing that best predicts who goes on to have serious liver problems.

If you’ve been told you have “fibrosis” or “scarring,” or if a report mentions “F2” or “F3,” this guide explains what the stages mean, how they’re measured without surgery, how likely they are to change, and what the guidelines recommend at each stage. It applies to MASLD (metabolic dysfunction-associated steatotic liver disease, formerly NAFLD) and its inflamed form MASH, formerly NASH.

What Are the Stages of Liver Fibrosis?

When the liver is injured over a long time, it repairs itself by laying down scar tissue. In fatty liver, the injury comes from fat and inflammation, which is why scarring is a feature of MASH. The scoring systems used by pathologists grade fibrosis from 0 to 4.

Stage	Name	What’s happening	Where it sits
F0	No fibrosis	No scarring	Normal
F1	Mild	Early scar tissue around small vessels or bile duct areas	Not considered significant
F2	Moderate (“significant”)	More scarring, extending beyond the early areas	Significant fibrosis (F2 or higher)
F3	Severe, bridging	Scar bands link up across the liver	Advanced fibrosis
F4	Cirrhosis	Widespread scarring that changes the liver’s structure	Advanced fibrosis; specialist care

Doctors use a few phrases for these ranges. “Significant fibrosis” means F2 or higher. “Advanced fibrosis” means F3 or F4: the AASLD defines it as bridging fibrosis (F3) or compensated cirrhosis (F4). “At-risk MASH,” the group the new medicines target, means MASH with moderate scarring or worse (stage F2 or higher). The 2005 NASH Clinical Research Network scoring system, which most fatty liver research uses, rates fibrosis from 0 to 4 along with fat, inflammation and cell ballooning. Different systems (such as METAVIR) use similar labels, so the same “F” number can be read slightly differently between them, and your doctor can tell you which one your report uses.

Why Does Fibrosis Stage Matter More Than Fat?

Because scarring is what damages the liver’s ability to work and predicts complications. Two long-term studies from Sweden make this clear.

In a study of 646 people with biopsy-proven fatty liver followed for an average of 20 years (Hagström et al.), 12% developed severe liver disease (cirrhosis, liver decompensation or failure, or liver cancer), compared with 2.2% of matched controls. The risk climbed with each stage of fibrosis, with hazard ratios compared with controls ranging from 1.9 at F0 to 104.9 at F4. Adding the presence of MASH (NASH at the time) to the models didn’t significantly improve prediction. The study’s estimates of how soon severe disease might appear were, at the cautious end, at least 22–26 years for F0–1, 9.3 years for F2, 2.3 years for F3 and 0.9 years for F4. These are statistical lower bounds from one cohort, not a forecast for any individual.

An earlier Swedish study of 229 people followed for up to 33 years found the same pattern: fibrosis stage predicted both overall and disease-specific death, while the inflammation score did not. People with stage 3–4 fibrosis had increased mortality (hazard ratio 3.3).

The AASLD summarizes similar findings in numbers per 100 person-years of follow-up: all-cause mortality of 0.32 for stages 0–2, 0.89 for bridging fibrosis and 1.76 for cirrhosis. It also says bridging fibrosis and cirrhosis carry an exponentially greater risk of liver-related morbidity.

The practical message is the same one our fatty liver grades guide makes: a “grade 3” for fat doesn’t tell you what a “stage 3” for scarring does. Knowing your stage is the most useful number in your liver care.

How Is Fibrosis Measured Without a Biopsy?

Most people with fatty liver are staged using non-invasive tests (NITs), in a two-step pathway recommended by both the AASLD and the 2024 European guideline.

Step 1: FIB-4. A formula using age, AST, ALT and platelet count, from routine blood work. The AASLD treats below 1.3 as low risk, and above 2.67 as high risk, with a cutoff of above 2.0 for people over 65. It has low accuracy under age 35. Try it in our FIB-4 calculator.

Step 2: a second test if FIB-4 is 1.3 or higher. The options are:

• FibroScan (vibration-controlled transient elastography). Stiffness below 8 kPa can rule out advanced fibrosis. Above 12 kPa is associated with a high likelihood of advanced fibrosis, and 20 kPa or more with cirrhosis. See FibroScan results explained.
• ELF blood test. The AASLD gives below 7.7 as the rule-out value; 9.8 or higher identifies patients at increased risk, and 11.3 or higher predicts future liver-related events.
• MR elastography or shear wave elastography. Other ways to measure stiffness, used in some clinics.

Test	Low risk	Higher risk
FIB-4	Below 1.3 (below 2.0 over 65)	Above 2.67
FibroScan stiffness	Below 8 kPa	Above 12 kPa; 20 kPa or more suggests cirrhosis
ELF	Below 7.7	9.8 or higher

The European guideline adds a second option for people with a middle FIB-4 (1.3 to 2.67): a year of lifestyle and cardiometabolic treatment, followed by elastography if FIB-4 is still elevated. For those with a low FIB-4, it suggests reassessment every one to three years.

Liver biopsy. This is the only test that shows the actual stage and confirms MASH, but the European guideline says it isn’t required in most cases. The AASLD suggests considering it when non-invasive tests point to significant fibrosis (F2 or higher), when results conflict or are indeterminate, when aminotransferases stay raised for more than six months, or when another liver disease is suspected. NIDDK lists similar reasons.

These tests estimate risk. They can be wrong in either direction, and they work best read together with your history, your platelet count and your other blood tests.

How Common Is Advanced Fibrosis in Fatty Liver?

It depends heavily on who you are. The AASLD estimates advanced fibrosis at roughly 0.9% to 2% of the general population, but 6% to 19% of people with type 2 diabetes, and 4% to 33% of those with medically complicated obesity. The same table lists 18% among first-degree relatives of someone with cirrhosis. These are broad ranges from varying studies, which is why the guidelines recommend screening for scarring in higher-risk groups instead of everyone.

Can Liver Fibrosis Be Reversed?

Sometimes, in the earlier stages, though it’s slower and less certain than losing liver fat. The best evidence in lifestyle comes from a 2015 Gastroenterology study (Vilar-Gomez et al.) of 293 people with biopsy-proven NASH who followed a lifestyle program for 52 weeks. Of those who lost 10% or more of their body weight, 45% had regression of fibrosis. Only 30% of the whole group lost even 5%, which shows how hard it is.

That’s consistent with the weight-loss targets in the 2024 European guideline: at least 5% for liver fat, 7–10% for inflammation, and 10% or more for fibrosis. The AASLD says greater weight loss (more than 10%) is generally required to improve MASH and fibrosis. Our guide to how to reverse fatty liver covers the habits behind those numbers.

No one can promise regression, and cirrhosis (F4) is much less likely to reverse. At that stage the aim shifts to preventing complications.

What Treatment Is Recommended at Each Stage?

Stage	General approach
F0–F1	Lifestyle changes (food, activity, weight, little alcohol) and control of blood sugar, blood pressure and cholesterol. Recheck FIB-4 periodically.
F2–F3 (no cirrhosis)	Everything above, plus a liver specialist’s input. Two medicines have regulatory approval, for MASH with F2–F3 fibrosis alongside diet and exercise: resmetirom and semaglutide (details on those pages).
F4 (cirrhosis)	Specialist care. No MASH-targeted drug is recommended for the cirrhotic stage by the European guideline. Surveillance for liver cancer and complications. Nutrition advice changes.

For cirrhosis, the European guideline recommends semi-annual abdominal ultrasound as the primary strategy for liver cancer surveillance, while noting that ultrasound has limits in people with MASLD. It also states that individuals with cirrhosis must abstain from alcohol. Protein needs and sodium limits differ from regular fatty liver advice, so follow your care team and see our cirrhosis diet guide.

Alcohol matters at every stage but especially from F2 up. With significant fibrosis or cirrhosis the advice is none. See alcohol and fatty liver.

What Should You Ask If You’ve Been Told You Have Fibrosis?

1. Which stage, and how was it measured? A FibroScan, FIB-4 and a biopsy don’t give the same kind of answer.
2. How confident are we? If results conflict, ask whether to repeat a test or try a different one.
3. Do I need to see a hepatologist? The AASLD advises specialist referral when non-invasive tests suggest intermediate or high risk.
4. What are my other risks? Diabetes, blood pressure, cholesterol and alcohol all affect the plan, and heart disease is a major concern in people with fatty liver.
5. When do we recheck, and with what?

The Bottom Line

Liver scarring is staged F0 to F4: none, mild, significant (F2), advanced (F3) and cirrhosis (F4). In fatty liver, the stage predicts future liver problems better than the amount of fat, which is why guidelines focus on finding out who has significant scarring. Most people can be staged with FIB-4 and a FibroScan or ELF test, with biopsy kept for unclear cases. Early stages can improve with sustained weight loss and better habits, two medicines are available for MASH with F2–F3 fibrosis, and cirrhosis calls for specialist care and a different nutrition plan. Ask for your stage; it’s the number worth knowing.

Sources

• AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease (Rinella et al., Hepatology 2023)
• EASL–EASD–EASO Clinical Practice Guidelines on the management of MASLD (Obesity Facts 2024)
• Hagström et al. Fibrosis stage but not NASH predicts mortality and time to development of severe liver disease in biopsy-proven NAFLD (Journal of Hepatology 2017)
• Ekstedt et al. Fibrosis stage is the strongest predictor for disease-specific mortality in NAFLD after up to 33 years of follow-up (Hepatology 2015)
• Vilar-Gomez et al. Weight loss through lifestyle modification significantly reduces features of nonalcoholic steatohepatitis (Gastroenterology 2015)
• Kleiner et al. Design and validation of a histological scoring system for nonalcoholic fatty liver disease (Hepatology 2005)
• NIDDK: Diagnosis of MASLD and MASH

This article is for informational purposes only and is not medical advice. Talk to your doctor or hepatologist about your specific situation.