The main causes of liver fibrosis, and what you can do

Liver fibrosis isn't a disease in itself. It's the scar left by a repeated injury to the liver, whatever its origin. To slow it down, or to help it regress, you need to act on what's damaging the liver. The good news is that the most common causes are also the ones you can act on. This article reviews them, starting with the most accessible, with what can be done about each.

One mechanism, several origins

Every time liver cells are destroyed, the organ repairs itself. If the injury is brief, it regenerates without a trace. If it lasts for years, the repair produces scar tissue, which builds up: this is fibrosis, classified from F0 (none) to F4 (cirrhosis).

Causes vary by region of the world. In France, the top three are alcohol use, steatosis linked to excess weight and diabetes, and viral hepatitis B and C, according to the French national professional council of hepato-gastroenterology. In the United States, where about 4.5 million adults have a diagnosed liver disease according to the CDC, alcohol and metabolic steatosis also dominate. Worldwide, viral hepatitis carries far more weight: the World Health Organization (WHO) estimates in its 2026 report that 240 million people live with chronic hepatitis B and 47 million with hepatitis C.

These causes often add up in the same person. Excess weight combined with regular alcohol use damages the liver faster than either one alone. This is also what makes action effective: reducing just one of these injuries already relieves the liver.

Causes you can act on

Alcohol

Alcohol is converted by the liver into a toxic substance, acetaldehyde, which directly damages liver cells. Risk increases with amount and duration, with no threshold below which it would be zero. It also varies between people: for the same consumption, women are more vulnerable, as are people who are overweight or have a viral hepatitis.

What you can do. In France, the lower-risk drinking guidelines are a maximum of 10 standard drinks per week, no more than 2 per day, with alcohol-free days. When fibrosis is already present, medical societies recommend reducing as much as possible, and stopping completely in cases of advanced fibrosis or cirrhosis. The effect is real at every stage: stopping alcohol allows the liver to partly repair itself and clearly improves life expectancy, even with cirrhosis. Cutting back alone can be difficult, and there's no shame in getting help: a primary care doctor, addiction medicine consultations, and France's Alcool Info Service helpline (0 980 980 930) are there for that. The Is my alcohol consumption risky? tool helps take stock.

Excess weight and steatosis

Excess abdominal fat promotes fat buildup in the liver. In some people, this fat triggers inflammation — steatohepatitis (MASH) — which is the real driver of fibrosis. As obesity rises, this cause is growing the fastest worldwide.

What you can do. Weight loss is the best-demonstrated treatment. A landmark study published in 2015 in Gastroenterology (Vilar-Gomez et al.) followed 293 people with steatohepatitis for one year. Among those who had lost at least 10% of their weight, steatohepatitis had resolved in 90% of cases and fibrosis had regressed in 45% of cases. A more modest loss, of 5 to 7%, already reduces fat and inflammation. This doesn't mean following a strict diet: the 2024 European guidelines recommend a Mediterranean-style diet, with fewer sugary drinks and ultra-processed foods. The Am I overweight or obese? tool helps place your BMI and waist circumference.

Type 2 diabetes

Type 2 diabetes is the factor that speeds up progression to fibrosis the most: it roughly doubles the risk of advanced fibrosis in people who have steatosis. Insulin resistance, which is at the heart of diabetes, increases both the arrival of fat in the liver and inflammation.

What you can do. Well-controlled diabetes protects the liver. Some diabetes treatments also have a favorable effect on weight and on the liver, which a doctor can factor into the choice of treatment. Guidelines also call for screening for fibrosis, via FIB-4, in everyone with type 2 diabetes. The Am I at risk of diabetes? tool is aimed at people who don't know they have diabetes.

Inactivity

Lack of physical activity affects the liver independently of weight. Conversely, muscles in motion burn fat and sugar and become more sensitive to insulin, which relieves the liver.

What you can do. Studies show a drop in liver fat of around 20 to 30% after a few months of regular activity, even when weight changes little. The recommended target is at least 150 minutes per week of moderate-intensity activity, such as brisk walking, cycling, or swimming, ideally combined with strength training. Every step counts: starting with ten minutes a day is already useful. The What is my physical activity level? tool helps assess your starting point.

Viral hepatitis B and C

These two viruses cause chronic liver inflammation, often with no symptoms for decades. According to the WHO, they caused 1.3 million deaths worldwide in 2024, mainly through cirrhosis and liver cancer. Many infected people don't know they have it.

What you can do. These are causes that medicine can now treat very well. Hepatitis C is cured in more than 95% of cases, with an 8-to-12-week course of pills. Hepatitis B can't yet be cured, but treatment blocks the virus, and an effective vaccine exists: it has been mandatory in France for infants born since 2018. Once the virus is controlled, fibrosis regresses. In a study published in 2013 in The Lancet (Marcellin et al.), after five years of hepatitis B treatment, fibrosis had regressed in 51% of patients, and 74% of those who started with cirrhosis no longer had it. The French Association for the Study of the Liver (AFEF) recommends that every adult be screened at least once in their life for hepatitis B and C, with a simple blood test.

Tobacco, medications, and supplements

Smoking is associated with faster fibrosis progression and increases the risk of liver cancer. Some long-term medications, as well as dietary supplements and herbal preparations, can also be toxic to the liver.

What you can do. Quitting smoking is beneficial at any age, and the Am I addicted to nicotine? tool can help prepare for this step. On the medication side, the simplest approach is to tell your doctor and pharmacist about everything you take, including “natural” products, and to respect doses, especially for acetaminophen (paracetamol). Never stop a prescribed treatment on your own. Finally, coffee, without sugar, is associated in many studies with a lower fibrosis risk, starting at two to three cups a day.

Causes you have less control over

Some causes don't depend on lifestyle. Age is one of them: fibrosis risk increases with the years. There are also genetic predispositions, such as the PNPLA3 gene variant, which promotes steatosis and its progression.

Other, rarer diseases damage the liver: hemochromatosis, a genetic iron overload disorder whose predisposition affects about one in 300 people in France, autoimmune hepatitis, bile duct diseases, or Wilson's disease. These can't be prevented, but they're treated all the more effectively when diagnosed early. Hemochromatosis, for example, is treated with simple, regular bloodletting. That's why an abnormal liver panel with no obvious cause always deserves further investigation.

Fibrosis can regress

For a long time, fibrosis was thought to be permanent. We now know it can regress when the underlying injury is removed or controlled, as shown by the studies cited above on weight loss and hepatitis treatment. This regression is slow, taking one to several years, and is more complete at early stages. Even at the cirrhosis stage, treating the cause reduces the risk of complications.

Medications directly targeting steatohepatitis with fibrosis are also starting to arrive, such as resmetirom, approved in the European Union in 2025. They apply to a minority of patients followed by a specialist and add to lifestyle measures, without replacing them.

What to remember

Most causes of fibrosis are identifiable and modifiable: alcohol, weight, diabetes, inactivity, viral hepatitis. There's no need to change everything at once. Every injury removed gives the liver more room to repair itself, and a primary care doctor can help decide where to start.

To estimate your fibrosis risk from a blood test, take the “Is my liver damaged?” test.