Overview
Non-alcoholic fatty liver disease (NAFLD) is a spectrum of conditions caused by fat accumulation in the liver in people who drink little or no alcohol. Most people have simple fatty liver (steatosis) which is harmless, but in some it progresses to inflammation (NASH), fibrosis, cirrhosis, and liver failure.
How common is it?
NAFLD is the most common liver condition in the UK, affecting around 1 in 3 adults to some degree. It is closely linked to the obesity epidemic.
Causes and risk factors
Excess calories, particularly from sugar and refined carbohydrates, are converted to fat in the liver. Insulin resistance, common in obesity and type 2 diabetes, accelerates this process.
Common risk factors
- Obesity, particularly abdominal (central) obesity
- Type 2 diabetes and insulin resistance
- High triglyceride levels
- Metabolic syndrome
- Polycystic ovarian syndrome
- Rapid weight loss or starvation diets
- Certain medications including steroids and tamoxifen
Symptoms
- Most people have no symptoms in early stages
- Fatigue
- Mild discomfort or aching in the upper right abdomen
- In advanced cirrhosis: jaundice, swollen abdomen (ascites), easy bruising, confusion
When to see a doctor
See a doctor if you have risk factors (obesity, type 2 diabetes) and any liver symptoms, or if a blood test has shown abnormal liver enzymes. Cirrhosis symptoms such as jaundice or swollen abdomen are urgent.
Diagnosis
Liver ultrasound identifies fat in the liver. Blood liver function tests are often abnormal. Liver biopsy or specialised MRI scoring (FibroScan) assesses the degree of fibrosis without biopsy.
Treatments
Weight loss
The most effective treatment. Loss of 7 to 10% of body weight reduces liver fat and inflammation significantly. Loss of over 10% can reverse fibrosis.
Management of metabolic risk factors
Controlling blood glucose, blood pressure, and cholesterol reduces the rate of disease progression and cardiovascular risk.
Emerging drug treatments
No drug is yet licensed specifically for NAFLD in the UK, but several are in late-stage trials. Pioglitazone, vitamin E, and GLP-1 receptor agonists (licensed for diabetes) have evidence for liver benefit.
Self-care and lifestyle
- Reduce sugar, sweetened drinks, white bread, and processed foods
- Follow a Mediterranean-style diet rich in olive oil, fish, and vegetables
- Exercise at least 150 minutes per week, including both aerobic and resistance exercise
- Avoid alcohol entirely or minimise it, as even modest intake worsens progression
Prevention
Maintaining a healthy weight through diet and exercise is the primary prevention. Treating type 2 diabetes and metabolic syndrome effectively reduces NAFLD risk and progression.