Non-alcoholic fatty liver disease (NAFLD)

What is NAFLD?

Non-alcoholic fatty liver disease (NAFLD) is a condition where fat builds up in the liver. It is not caused by alcohol. The NHS describes it as very common and often discovered incidentally during blood tests or scans done for other reasons.

In 2023 the global nomenclature shifted to MASLD (metabolic dysfunction-associated steatotic liver disease), but NAFLD remains the term most people recognise and the NHS still uses it. This page uses both terms so readers can recognise either.

Why it matters

Most people with NAFLD will not develop serious problems. However, for some it can progress to inflammation (steatohepatitis), fibrosis, and in a minority, cirrhosis or liver cancer. The BSG/BASL quality standards emphasise early identification and risk-factor management to prevent progression.

Common risk factors

• Overweight or obesity, especially abdominal weight
• Type 2 diabetes or insulin resistance
• High blood pressure
• High cholesterol or triglycerides
• Polycystic ovary syndrome (PCOS)
• Family history of metabolic syndrome

NAFLD is not caused by alcohol. Do not confuse it with alcohol-related liver disease (ARLD), which is a different condition with different management.

Symptoms

NAFLD usually causes no symptoms in the early stages. Some people may experience:

• Tiredness or fatigue
• Discomfort in the upper right abdomen
• Unexplained weight loss in advanced cases

Because it is often silent, the diagnosis is usually made when liver blood tests or scans are done for another reason.

Diagnosis

• Blood tests (liver function tests) may show raised liver enzymes, but normal results do not rule out NAFLD.
• Ultrasound can detect fatty change in the liver.
• FibroScan (transient elastography) assesses liver stiffness and fat content non-invasively.
• Liver biopsy is reserved for selected cases where the degree of fibrosis is unclear.

Approaches people discuss

NICE NG49 makes clear that first-line management is lifestyle change. There are no medicines approved specifically for NAFLD on the NHS.

• Established Lifestyle change as first-line management: gradual weight loss (NICE NG49 suggests 5–10% if overweight), healthier eating patterns, and increased physical activity. This is the cornerstone of NHS and NICE care. Sources: NHS NAFLD; NICE NG49.
• Established Managing metabolic risk factors alongside NAFLD: blood pressure, cholesterol, and glucose control through standard NHS pathways. Sources: NICE NG49.
• Emerging Dietary patterns high in fibre and Mediterranean-style diets may benefit liver fat via effects on gut microbiota. A 2025 Nutrients review and BSG/BASL consensus note diet quality, but specific microbiome-targeted dietary protocols are not yet standard NHS care. Sources: Nutrients 2025; BSG/BASL quality standards.
• Emerging The gut microbiome is altered in NAFLD/MASLD and microbial metabolites may influence liver inflammation and fibrosis. 2024–2025 reviews describe gut–liver axis associations, but clinical translation is not yet guideline-recommended. Sources: Nature Reviews Gastroenterology & Hepatology 2025.

What not to self-manage

These are cautions, not approaches people discuss:

• Do not treat probiotics, prebiotics, or faecal microbiota transplantation as proven NAFLD treatments — not supported by current NICE or BSG/BASL guidance.
• Do not use “liver detox” products, unproven supplements, or extreme liver-cleansing diets — the NHS does not recommend these.