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Health condition · Clinically reviewed

Fatty liver disease, MASLD, MASH and a new era of treatment.

The UK's most common liver disease, renamed in 2023 and reshaped by modern non-invasive tests, GLP-1 agonists and the first MASH-specific drug.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE NG49, EASL, BSG and peer-reviewed hepatology sources you can see at the end.

  • 03

    Current for 2026

    Reflects the new MASLD and MASH nomenclature, FIB-4 and FibroScan pathways, and resmetirom.

Key facts

Fatty liver disease at a glance.

The essentials, in plain English - the new nomenclature, how common it is, how it progresses and how it is treated in the UK today.

  • What it is

    Excess fat in the liver above 5 percent of hepatocytes, most often driven by cardiometabolic risk factors.

  • New name in 2023

    MASLD (metabolic dysfunction-associated steatotic liver disease) replaces NAFLD. MASH replaces NASH.

  • How common

    Around 25 to 30 percent of UK adults have MASLD, making it the most common liver disease in the country.

  • How it progresses

    Simple steatosis to MASH to fibrosis (F0 to F4) to cirrhosis, with a real risk of hepatocellular carcinoma.

  • Foundation of care

    A 7 to 10 percent weight loss, Mediterranean diet, exercise and treatment of metabolic risk factors.

  • New drug era

    Resmetirom is the first drug approved specifically for MASH with F2 to F3 fibrosis. GLP-1 agonists play a growing role.

Why this guide matters

A metabolic disease with a cardiovascular tail.

Fatty liver disease is common, mostly silent and shares its risk factors with heart disease and diabetes. The three points below shape everything else on this page.

  • MASLD is a metabolic diagnosis

    It sits alongside obesity, type 2 diabetes, hypertension and dyslipidaemia - not a separate silo. Treating one helps the others.

  • Fibrosis is the number that matters

    Simple fat is common and often benign. Fibrosis stage predicts long-term outcomes and drives decisions about drugs, surveillance and referral.

  • Effective options exist

    Weight loss, GLP-1 agonists, bariatric surgery and now resmetirom for MASH have moved fatty liver disease from watchful waiting to active treatment.

How the diagnosis is made

From an odd LFT to a clear fibrosis stage.

The steps a UK GP or hepatologist will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    Bloods and cardiometabolic review

    LFTs, GGT, FBC, U and Es, lipids, HbA1c, iron studies, ferritin, autoimmune screen, coeliac and viral hepatitis (A, B, C and E).

  2. 02

    Assessing

    FIB-4 score

    Age, AST, ALT and platelets combined into the UK first-line non-invasive fibrosis score. Guides who needs specialist review.

  3. 03

    Assessing

    Liver ultrasound

    Looks for steatosis, hepatomegaly, splenomegaly and any early signs of portal hypertension.

  4. 04

    Confirming

    ELF blood test

    Enhanced Liver Fibrosis test refines risk when FIB-4 is intermediate or unclear.

  5. 05

    Confirming

    Transient elastography (FibroScan)

    Measures liver stiffness in kilopascals and CAP for steatosis. Specialist commissioned - see /treatments/fibroscan-liver/.

  6. 06

    Specialist

    MRI-PDFF and MR elastography

    Gold standard non-invasive measurement of fat and fibrosis, used in specialist hepatology and clinical trials.

  7. 07

    Specialist

    Liver biopsy where needed

    Reserved for diagnostic uncertainty or intermediate risk that non-invasive tools cannot settle - see /treatments/liver-biopsy/.

Typical timeline: from a first blood test to a fibrosis stage in a matter of weeks.

Symptoms

What fatty liver disease actually feels like.

For most people, the honest answer is - not much. But there are subtle clues, and there are the features that mean it has moved beyond simple steatosis.

  • Often silent

    Most MASLD is picked up incidentally on LFTs or an ultrasound done for another reason.

  • RUQ discomfort

    A dull ache or fullness in the upper right abdomen, sometimes with a sense of pressure.

  • Fatigue

    A persistent, low-grade tiredness that does not track cleanly with sleep or activity.

  • Hepatomegaly

    An enlarged liver felt on examination, often the first physical clue in otherwise well people.

  • Metabolic pattern

    Central obesity, type 2 diabetes, hypertension or dyslipidaemia - the cardiometabolic backdrop of MASLD.

  • Jaundice and ascites

    Late features - yellow skin, abdominal swelling and leg oedema point to advanced disease.

  • Encephalopathy and bleeding

    Confusion or variceal bleeding are cirrhosis-level warnings - see /conditions/hepatic-encephalopathy/ and /conditions/esophageal-varices/.

  • Red flag - HCC risk

    Once cirrhotic, six-monthly ultrasound and AFP surveillance for liver cancer is essential - see /conditions/liver-cancer/.

Treatment

How fatty liver disease is treated in the UK.

Lifestyle first, metabolic and cardiovascular risk factors next, and now a specific pathway for MASH with meaningful fibrosis.

  • Lifestyle - the foundation

    A 7 to 10 percent weight loss is the single most effective intervention. Mediterranean diet, fewer simple carbs, 150 minutes of exercise a week, less alcohol and no smoking.

  • Specialist weight management

    For obesity, structured NHS or private weight-management pathways with dietetic and psychological input.

  • GLP-1 agonists

    Semaglutide and tirzepatide reduce weight, improve glycaemic control and lower hepatic fat. See /treatments/glp-1-weight-loss-clinic/.

  • Bariatric surgery

    Highly effective for selected patients with severe obesity - resolves MASH and reduces fibrosis in many cases.

  • Diabetes therapies

    SGLT2 inhibitors, GLP-1 agonists and pioglitazone reduce hepatic fat and inflammation alongside their glycaemic benefit.

  • Lipid and blood pressure care

    Statins are safe in MASLD and important for cardiovascular risk. Blood pressure is treated to standard NICE targets.

  • Resmetirom (Rezdiffra)

    The first drug approved specifically for MASH with F2 to F3 fibrosis - a thyroid hormone receptor beta agonist. See /treatments/resmetirom-mash-clinic/.

  • Cirrhosis and transplant care

    Six-monthly HCC surveillance, variceal screening, encephalopathy management and, for decompensated disease, referral for liver transplantation.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your GP or hepatologist knows your bloods, imaging and full history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Non-alcoholic fatty liver disease (NAFLD): assessment and management (NG49).

  • EASL-EASD-EASO. Clinical practice guidelines on the management of metabolic dysfunction-associated steatotic liver disease (MASLD).

  • British Society of Gastroenterology (BSG). Guidance on non-invasive assessment of liver fibrosis.

  • AASLD, EASL and ALEH. Multi-society Delphi consensus on new fatty liver disease nomenclature (MASLD, MASH, MetALD).

  • FDA. Resmetirom (Rezdiffra) approval for adults with non-cirrhotic MASH with moderate to advanced fibrosis.

Red flags

When fatty liver disease needs urgent attention.

Most MASLD is managed in primary care with hepatology support. These are the features that push a case up the queue.

  • Jaundice

    Yellowing of the skin or eyes suggests significant hepatic dysfunction and needs same-week specialist assessment.

  • Ascites or leg oedema

    Abdominal swelling or leg oedema in fatty liver disease often signals decompensated cirrhosis.

  • Hepatic encephalopathy

    Confusion, drowsiness, disturbed sleep-wake cycle or flapping tremor is a hepatology emergency - see /conditions/hepatic-encephalopathy/.

  • Variceal bleeding

    Haematemesis or melaena in a patient with liver disease is a 999 call - see /conditions/esophageal-varices/.

  • Rapidly rising LFTs

    A sudden jump in transaminases points away from stable MASLD and towards drug injury, viral hepatitis or autoimmune flare.

  • Suspected HCC

    A new liver lesion, rising AFP or weight loss in a cirrhotic patient needs urgent liver MDT review - see /conditions/liver-cancer/.

  • Persistently high ferritin

    Very high ferritin with raised transferrin saturation warrants a haemochromatosis screen alongside MASLD assessment.

  • Alcohol misuse

    Where alcohol intake is above thresholds, MetALD or alcohol-related liver disease reshapes the plan and prognosis.

  • Pregnancy with severe MASLD

    Pregnancy in advanced liver disease is high risk and needs joint hepatology and obstetric care.

Living with it

A treatable condition, with a clear ladder.

Four things that make the biggest difference day to day - weight, plate, movement and alcohol. Simple in theory, harder in practice, and worth the effort.

A quiet reminder

Consistency beats intensity, every time.

Small, steady habits kept up for months do more for your liver than a heroic month that does not last.

  1. 01 Weight

    Aim for 7 to 10 percent

    This is the evidence-based threshold that resolves MASH in a meaningful proportion of people and reduces fibrosis. Every kilogram counts.

  2. 02 Plate

    A Mediterranean pattern

    More olive oil, fish, pulses, vegetables and whole grains. Fewer ultra-processed foods, sugar-sweetened drinks and refined carbs.

  3. 03 Movement

    150 minutes a week

    A mix of aerobic activity and resistance training reduces hepatic fat even without dramatic weight loss.

  4. 04 Alcohol

    Less is more, always

    Alcohol amplifies liver injury in MASLD. In cirrhosis or MetALD the safest amount is none.

Frequently asked

Everything we get asked about fatty liver disease.

Quick answers on MASLD, MASH, non-invasive fibrosis testing, GLP-1 agonists and resmetirom.

  • What is MASLD and how is it different from NAFLD?

    MASLD (metabolic dysfunction-associated steatotic liver disease) is the 2023 replacement for NAFLD. It requires more than 5 percent hepatic fat plus at least one cardiometabolic risk factor - obesity, type 2 diabetes, hypertension or dyslipidaemia. The change reflects the fact that the driver is metabolic dysfunction, not the absence of alcohol.

  • What is MASH?

    MASH (metabolic dysfunction-associated steatohepatitis) is the inflammatory, progressive form of MASLD. It carries a real risk of fibrosis, cirrhosis and hepatocellular carcinoma, and it is the form that specifically warrants pharmacological treatment with agents like resmetirom.

  • How is fibrosis measured without a biopsy?

    The UK pathway starts with FIB-4, calculated from age, AST, ALT and platelets. Intermediate or high scores lead to ELF, transient elastography (FibroScan) or, in specialist centres, MRI-PDFF and MR elastography. Biopsy is reserved for diagnostic uncertainty.

  • How much weight loss actually helps?

    A 7 to 10 percent loss of body weight is the target supported by the strongest evidence. At that level, MASH resolves in a meaningful proportion of people and fibrosis can regress. Smaller losses still reduce hepatic fat and cardiovascular risk.

  • Where do GLP-1 agonists fit in?

    Semaglutide and tirzepatide reduce weight, improve glycaemic control and lower hepatic fat. They are particularly useful when obesity or type 2 diabetes coexist with MASLD, and dedicated MASH trials continue to expand their role.

  • What is resmetirom?

    Resmetirom (Rezdiffra) is a thyroid hormone receptor beta agonist and the first drug approved specifically for MASH with moderate to advanced fibrosis (F2 to F3). It is FDA-approved and awaiting EMA and MHRA decisions, and is specialist commissioned in the UK.

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