Medical Encyclopaedia › Fatty liver (short definition)
In brief: In fatty liver, more than about five per cent of the liver cells are filled with fat. The most common form is linked to overweight and metabolic disorders and is now called MASLD (metabolic dysfunction-associated steatotic liver disease). It affects about one in four adults.
Causes
The main causes are overweight, especially abdominal fat, insulin resistance and type 2 diabetes, raised blood lipids and lack of exercise. A lot of sugar and fructose in drinks promotes fat accumulation. Alcohol, certain medicines and rare diseases can also cause fatty liver.
Symptoms and consequences
Fatty liver usually causes no symptoms and is often discovered by chance on ultrasound or through raised liver values. In some of those affected, the liver becomes inflamed (MASH) and gradually scars. Over the years, liver cirrhosis with an increased risk of liver cancer can develop. People with fatty liver also have an increased cardiovascular risk.
Diagnosis
In addition to ultrasound and liver values, the risk of scarring is estimated using simple scores such as the FIB-4 index. If the values are abnormal, liver stiffness is measured (elastography); a tissue sample is only rarely necessary.
What helps?
Weight loss is the most effective measure: even five to ten per cent less body weight can significantly reduce fat and inflammation in the liver. A balanced, low-sugar diet, for example along Mediterranean lines, regular exercise, avoiding alcohol and treating diabetes and blood lipids are recommended. In advanced disease, medicines may also be considered; their use is decided by a doctor.
When to see a doctor?
Raised liver values or fatty liver found on ultrasound should be assessed by a doctor, especially in people with diabetes or overweight. Yellowing of the skin, fluid in the abdomen or a tendency to bleed require prompt investigation.
Related terms in the encyclopaedia
Liver, Liver values, Liver cirrhosis, Insulin resistance, Metabolic syndrome, Visceral fat, Type 2 diabetes, Mediterranean diet, Ultrasonography
Sources
- Deutsche Gesellschaft für Gastroenterologie, Verdauungs- und Stoffwechselkrankheiten (DGVS): S2k-Leitlinie MASLD, AWMF-Register 021-025
- EASL, EASD, EASO: Clinical Practice Guidelines on the Management of MASLD 2024
- IQWiG: gesundheitsinformation.de – Gesundheitsinformationen des Instituts für Qualität und Wirtschaftlichkeit im Gesundheitswesen
Note: This article is for general information and does not replace advice, diagnosis or treatment from a doctor or pharmacist. Last updated: October 2026.