Obesity and fatty liver disease

Fatty liver disease

The liver plays a vital role in digesting food, storing and releasing energy, removing toxins from the body's blood supply and helping fight infections. Fatty liver disease is a common condition where excess fat accumulates in the liver, to the extent that it disrupts the normal functioning of the liver. There are two types.

The first type is alcoholic fatty liver disease, which may also be referred to as alcoholic steatohepatitis. It is caused by drinking large amounts of alcohol. The NHS explains that it is the first stage of alcohol-related liver disease (ARLD). It adds that alcoholic fatty liver disease rarely causes any symptoms and can be reversed by not consuming alcohol for an extended period (months or years).

The other type is non-alcoholic fatty liver disease (NAFLD), which is increasingly being referred to as metabolic dysfunction-associated steatotic liver disease (MASLD). NAFLD is unrelated to alcohol use. It is associated with being overweight and having an unhealthy diet. It does not typically cause any symptoms which makes it difficult to detect. The NHS also notes that a person is more likely to get non-alcoholic fatty liver disease if they have:

• high blood pressure,
• type 2 diabetes, or
• polycystic ovary syndrome.

It is also more common in people aged over 50 years.

There are four stages of NAFLD:

1. Fatty liver (steatosis): the 1st stage, where there is build-up of fat but no damage to your liver.
2. Non-alcoholic steatohepatitis (NASH): a build-up of fat has caused inflammation in your liver. It is not yet seriously damaged, but there's a risk it could get worse. NASH is increasingly being referred to as metabolic dysfunction-associated steatohepatitis’ (MASH).
3. Fibrosis: there is damage to your liver, but it will usually still be working well. It's important to try to stop further damage which could lead to cirrhosis.
4. Cirrhosis: there is severe damage to your liver that will affect how well it works. This could cause serious health problems including internal bleeding, liver failure, liver cancer or sepsis. Cirrhosis is advanced, irreversible scarring of the liver.

Many organisations have chosen to replace the terms NAFLD and NASH with MASLD and MASH, to reflect the metabolic profile of the condition, and avoid potentially stigmatising language.

The National Institute for Health and Care Excellence (NICE) has published a clinical knowledge summary on the management of non-alcoholic fatty liver disease in primary care. It advises clinicians to explain to patients that there is no specific medicine licensed for the management of the condition. Rather, the aim of management is to reduce the risk of the condition progressing, by making lifestyle changes to diet and physical activity to encourage weight loss.

Lifestyle changes, including losing weight, exercising regularly and eating a healthy, balanced diet are the main treatments for non-alcoholic fatty liver disease. No medicines have been approved (licenced) in the UK to treat non-alcoholic fatty liver disease.

NICE is currently developing guidance on MASLD which will partially replace its 2016 guidance on the assessment and management of NAFLD. NICE has noted that there are new drug treatments in late-stage clinical trials which may be covered in a future update of the MASLD guidance (PDF).

Statistics on non-alcoholic fatty liver disease

Specific figures for the prevalence of non-alcoholic fatty liver disease (NAFLD) in the UK are not available, but global estimates suggest that 25–33% of adults may be affected.

Data is available on the number of deaths in England due to NAFLD. The figures below show the number of deaths due to NAFLD and associated mortality rates for 2013 to 2023 (the latest data available). Over this period the number of deaths and the associated mortality rate was highest in 2023.

Please note the mortality rates shown here are not adjusted for changes in the size and age-structure of the population which can have an impact on the prevalence of alcohol-related conditions.

Source: DHSC Liver Disease Profiles – under 75 mortality data

Government policy on obesity

Public health is a devolved policy area. This overview relates to England only.

The government published its 10 year Health Plan for England in July 2025. In it, the government said it would “launch a moonshot to end the obesity epidemic”. As part of that, the government set out plans to restrict junk food advertising targeted at children, consider reforms to the soft drinks industry levy and introduce mandatory healthy food sales reporting for all large companies in the food sector.

Further information on the government’s work on obesity is available in Library briefings:

• Obesity statistics (February 2025) covers statistics on obesity among adults and children in the UK
• Weight loss medicines in England (April 2025), provides information on the availability of weight loss medicines in England. Section 1 provides an overview of weight loss treatment and services in England.
• Obesity policy in England, (June 2023), provides background on earlier government policy in England.
• Advertising of HFSS food and drink to children (July 2025) summarises regulation on junk food advertising

Further reading

• NHS, Non-alcoholic fatty liver disease (NAFLD)
• British Liver Trust, What is fatty liver (steatotic liver disease)
• Johns Hopkins Medicine, Non-alcoholic Fatty Liver Disease
• House of Commons Library, Health inequalities in liver disease and liver cancer