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Important
This article is general information about fatty liver disease, not medical advice or a recommendation, and it does not replace assessment by a qualified professional. Always see an appropriate healthcare professional about your own symptoms, diagnosis and treatment, including before starting, stopping or changing any medication or supplement. The treatment summaries here are for general understanding only and are not prescribing guidance.
Key points
- Fatty liver disease is a build-up of fat in the liver. When this is not due to excess alcohol it is called MASLD (previously NAFLD).
- It is extremely common, usually causes no symptoms, and strongly linked to insulin resistance and poor metabolic health.
- In some people it progresses to inflammation, scarring (fibrosis) and, eventually, cirrhosis.
- It often improves quickly when the sugar and excessive food (fuel) is reduced and metabolic health restored. The liver can usually recover well.
- It is both a consequence of poor metabolic health and a driver of further metabolic disturbance.
What it is
Fatty liver disease is the accumulation of excess fat within liver cells. When this occurs, and it is not due to excessive alcohol, it is called metabolic (dysfunction)-associated steatotic liver disease, or MASLD. This name replaced the older term "non-alcoholic fatty liver disease" (NAFLD) in 2023. The new name describes what the disease is (linked to metabolic dysfunction) rather than what it is not (linked to alcohol), and it requires evidence of at least one metabolic risk factor, such as excess weight, raised blood sugar or high blood pressure. It exists on a spectrum: simple fatty liver (fat alone), then steatohepatitis (fat plus inflammation, previously NASH, now MASH), then fibrosis (scarring), and finally cirrhosis (advanced, permanent scarring).
It is one of the most common liver conditions in the world, affecting a large proportion of adults, and it is closely linked to poor metabolic health. It can be thought of as the liver's expression of insulin resistance.
What causes it, and who is at risk
The underlying cause is excessive fat building up in the liver. There are two major drivers for this: the body's safe fat stores are full, and a diet high in sugar and refined carbohydrate. This causes the liver to make fat to try to get rid of the sugar. Fructose, a sugar found in many sweet foods, sugary drinks and sweet fruit, is a particular driver of fat build-up in the liver. People who are more obviously at risk include those with excess belly fat, prediabetes or type 2 diabetes, raised blood fat (triglycerides) and high blood pressure. Physical inactivity and stress can both contribute.
Symptoms and signs
Fatty liver usually causes no symptoms and is often found by chance. Advanced liver disease, called cirrhosis, can cause many symptoms such as jaundice, swelling in the abdomen and body, and blood clotting problems.
How it is diagnosed
It is often first suspected from mildly abnormal liver blood tests, though these can be normal even when fat is present. An ultrasound scan can show fat in the liver. If assessing for more advanced disease or scarring (fibrosis), clinicians can use blood-based scores (such as FIB-4) and specialised scans (such as transient elastography, sometimes called a FibroScan); occasionally a liver biopsy is needed. Assessment of fibrosis is the key step, as it identifies the minority at higher risk.
The metabolic health perspective
Fatty liver is, in essence, fat in the liver that shouldn’t be there. This is called ectopic fat and is central to insulin resistance. It is both an effect of and a cause for poor metabolic health. This is why fatty liver so often occurs with other conditions such as prediabetes, high blood pressure, type 2 diabetes, and a large waist.
Liver fat responds quickly to change, often faster than fat stored elsewhere in the body. Reducing the sugar, carbohydrate and total fuel (food) intake can lead to significant improvement.
Treatment and management
The aims are to clear liver fat, prevent or reverse inflammation and scarring, and improve the underlying metabolic health. The major focus is lifestyle change, and there are emerging medications for more advanced disease.
Lifestyle and the Health Foundations
This is the main treatment and is highly effective for simple fatty liver.
Nutrition
Reducing sugar, sugary drinks (especially those containing fructose), refined carbohydrate and ultra-processed food directly reduces the fat the liver makes and stores. Build meals around at least a palm-sized portion of protein, fill most of the rest of the plate with non-starchy vegetables, add natural fats for flavour, and treat starchy carbohydrate (bread, rice, pasta, potatoes) as an optional extra rather than a fixed portion. Many people with fatty liver do well keeping total carbohydrate under about 130g a day; some, especially if more insulin-resistant, improve further going lower, toward 70g a day or less. These are starting points to test, not fixed rules. Where there is excess weight, losing around 7 to 10% of body weight can substantially reduce fat and inflammation, though benefit begins before that.
Movement
Both aerobic and resistance exercise reduce liver fat, even without much weight change.
Alcohol
Minimising alcohol is important, as it adds directly to liver fat and damage.
Sleep and stress
Both support the wider metabolic improvement.
Other non-pharmaceutical options
- Vitamin E has evidence for reducing inflammation in selected people with confirmed steatohepatitis, but only under specialist guidance, as it is not suitable for everyone.
- Coffee (without added sugar) is associated with lower liver-disease risk in some research studies. But the evidence is not strong enough to suggest people should start drinking coffee if they currently do not.
- Correcting vitamin D if low, and being cautious with unnecessary supplements that can stress the liver, is sensible. Discuss any supplement with your pharmacist or clinician.
Medical and pharmaceutical treatments
There is no long-established drug specifically for simple fatty liver, but treatments for the more advanced disease, steatohepatitis (MASH), are now emerging. Medications used for related conditions, particularly some GLP-1-based and SGLT2 treatments, can reduce liver fat and, in some cases, fibrosis. Managing type 2 diabetes, blood pressure and blood fats is part of overall care, and people with significant fibrosis are followed up by liver specialists.
Complications and outlook
Most people with simple fatty liver do well, especially if they undertake the key lifestyle improvements. A minority of people progress to steatohepatitis, fibrosis and cirrhosis, with risks of liver failure and liver cancer; fatty liver also independently raises cardiovascular (heart and stroke) risk. The outlook is good when caught early: simple fatty liver is often fully reversible, and even fibrosis can stabilise or improve with sustained metabolic-health change.
When to see a doctor
- See your clinician if liver blood tests are abnormal, or if you have risk factors such as type 2 diabetes, a large waist or raised triglycerides.
- Seek prompt help for jaundice, abdominal swelling or other signs of advanced liver disease.
- Discuss alcohol intake honestly, as it strongly affects the liver.
Summary
- Fatty liver disease (MASLD, formerly NAFLD) is fat in the liver linked to insulin resistance, not alcohol.
- It is very common and usually silent, but can progress to inflammation, scarring and cirrhosis in some people.
- It is both a result and a driver of poor metabolic health, worsening blood sugar and blood fats.
- Reducing sugar, carbohydrate and total fuel (food) intake, plus physical activity and where needed modest weight loss, can clear liver fat.
- Assessing the degree of scarring may be appropriate, and specialists manage more advanced disease.
Health Shelf, healthshelf.org · Dr Campbell Murdoch, GP, UK · Reviewed August 2026
This is general information, not medical advice. Always speak to a qualified healthcare professional about your own symptoms and treatment, including before changing any medication.