It is a condition that affects a staggering 1.5 billion people worldwide – yet the majority are unaware they have it because, in its early stages, it causes no symptoms.
Fatty liver disease is driven by poor diet and obesity – distinct from alcohol-related liver disease, which is caused by heavy drinking – and is a leading driver of serious illness, driving a surge in cases of cirrhosis, liver failure and deadly liver cancer.
Now, experts say they have identified an early warning sign that could help spot those at risk: excess fat carried around the stomach.
Also known as central fat, this body shape markedly increases the risk of developing the disease, according to Dr Gautam Mehta, a liver specialist at Royal Free London NHS Foundation Trust.
Concerningly, many people with excess belly fat can still have a ‘healthy’ body mass index (BMI), meaning they are not classed as overweight – one of the main indicators GPs currently rely on when assessing liver disease risk.
Evidence suggests these patients may also be more likely to develop a particularly aggressive, and therefore life-threatening, form of the condition.
‘We call this lean fatty liver disease,’ says Dr Mehta.
‘Patients have this altered body shape but a normal BMI. Recent evidence shows they can develop a more aggressive form of liver disease.’
Experts say that many patients with excess belly fat can have a healthy body mass index (BMI), meaning they are not considered overweight, meaning GPs may not test them for liver disease.
But experts say there are steps patients can take to get rid of their excess belly fat.
So, what exactly is fatty liver disease? And how can you shrug off that large belly?
Liver disease occurs when the vital organ, which removes toxins from the blood, stops working properly. For some, this can be triggered by excessive drinking, which eventually scars the liver.
But for a growing number, poor diet and obesity are to blame.
The British Liver Trust estimates fatty liver disease may now affect one in five people in the UK – around 13 million adults – while in the United States it is thought to affect around one in four adults, equivalent to roughly 80 to 100 million people.
Caught early, the condition can be reversed, typically through diet changes and exercise. But experts say many patients are diagnosed at a stage when the liver is irreversibly damaged. When this happens, the condition can trigger organ failure and death.
Liver disease, in all its forms, is now the second most common cause of preventable deaths in the UK, after cancer.
At present, around 80 per cent of those affected remain undiagnosed, as the disease often has no obvious symptoms.
The lack of symptoms in the early stages is one of the main reasons experts are so concerned about the surge in cases
Research shows that some of the most common symptoms of fatty liver disease are fatigue, skin itching and yellowing skin – known as jaundice. However, experts say these only occur when the liver begins to fail, meaning it can be too late to reverse.
For this reason, experts say that excess stomach fat can often be one of the earliest signs that a patient may be at risk of liver disease.
Experts say a large belly raises the risk of liver disease because it signals the build-up of a particularly dangerous type of fat.
Known as visceral fat, it accumulates deep within the abdominal cavity, surrounding vital organs.
Research shows it is far more harmful than subcutaneous fat – which sits just beneath the skin – because it is metabolically active, releasing inflammatory chemicals that promote fat build-up in the liver and other organs.
Studies show that, over time, high levels of visceral fat can trigger type 2 diabetes – the condition marked by chronically high blood sugar levels. Experts believe this happens because visceral fat interferes with the body’s ability to respond to insulin, the hormone that helps lower blood sugar.
In turn, people with type 2 diabetes are significantly more likely to develop fatty liver disease than those without the condition, as persistently raised blood sugar and insulin resistance place added strain on the liver and promote fat build-up within the organ.
‘We’ve known for some time that excess central fat is closely linked to diabetes,’ says Dr Gautam Mehta. ‘And we know, in turn, that diabetes can lead to liver disease.’
Type 2 diabetes – which is on the rise in the UK – markedly increases the risk of liver disease
However, there is also growing evidence that visceral fat also damages the liver directly. Research suggests that, due to the proximity of belly fat to the liver, which sits at the top right of the stomach, fatty acids are released directly into the organ, inhibiting its function.
Experts say this would explain why certain ethnic groups are more at risk of liver disease.
‘Location of fat tends to vary by race,’ says Dr Mehta. ‘We know, in the UK, that South-East Asians are more likely to develop the condition. Higher levels of central fat could explain this.’
For this reason, experts say that patients should measure their waist size to quantify their liver disease risk.
For men, a waist measurement above 94cm (around 37 inches) is considered concerning, according to the NHS.
For women, the threshold is anything above 80cm (around 31.5 inches).
Such is the concern that last year experts called for a major revision of how obesity is defined, warning that millions of people with dangerous levels of body fat are being missed under the current system.
In a landmark report, an international panel of specialists argued that relying on BMI alone is outdated and misleading, because it fails to account for where fat is stored in the body – a factor increasingly linked to diabetes, heart disease, liver disease and early death.
They warned that excess fat around the waist poses a far greater risk to health than overall weight alone, yet is often ignored in routine health checks.
But, experts say there are steps patients can take to avoid a buildup of visceral fat.
Studies show regular exercise – such as brisk walking, cycling or swimming – can help reduce visceral fat.
Research suggests that completing around 150 to 300 minutes of moderate-intensity exercise a week can lead to meaningful reductions in abdominal fat over time, even without weight loss.
Getting seven to nine hours of sleep a night also appears protective, according to research, because poor sleep raises levels of the stress hormone cortisol, which drives fat storage in the abdomen.
Research has also shown that people who regularly drink alcohol are more likely to develop excess visceral fat.
‘We know that people who regularly drink more than eight units of alcohol a week – roughly four pints of beer or four medium glasses of wine – are more likely to go on to develop fatty liver disease,’ says Dr Gautam Mehta, whose team at Royal Free London NHS Foundation Trust earlier this month announced a landmark study investigating whether personalised diets could help prevent the condition.
Diet also plays a key role. Studies show that very low-calorie diets, typically providing around 800 calories a day for eight to 12 weeks, can dramatically reduce liver fat, even before major weight loss occurs.
‘Consuming red meat, refined carbohydrates – such as white bread, chips and pastries – and sugary drinks have all been linked to fatty liver disease,’ Dr Mehta adds.
Weight-loss injections have also been shown to significantly reduce visceral and liver fat.
Studies suggest drugs known as GLP-1 receptor agonists help drive fat loss from deep abdominal stores and can lead to substantial reductions in liver fat within months, even before dramatic overall weight loss occurs.
Experts say this may help explain why the jabs appear to lower the risk of type 2 diabetes, heart disease and fatty liver disease alongside shrinking waistlines.
