People who spend long periods of time sitting, and who do not exercise much, are at an increased risk of developing liver disease, a new study has found.

According to experts, ‘the message is clear, our chairs are slowly but surely killing us'.

Non-alcoholic fatty liver disease (NAFLD) refers to an accumulation of fat in the liver of people who consume little or no alcohol. While many people affected experience no symptoms or complications, others can suffer inflammation and scarring of the liver.

People with NAFLD also have an increased risk of developing heart disease and type 2 diabetes, and at its most severe, liver failure can occur.

While it is already widely acknowledged that a lack of exercise increases the risk of chronic diseases, such as diabetes and heart disease, an increasing number of studies are now focusing on sedentary behaviours.

Currently, the average person spends more than half of their day involved in sedentary activities, such as watching television or sitting using a computer or other electronic device.

Researchers in Korea looked at almost 140,000 middle-aged men and women. All had undergone a detailed health examination between 2011 and 2013 and their activity levels were also assessed.

The study found that almost 40,000 of the participants had NAFLD. It also found that prolonged sitting and decreased activity levels were independently associated with an increasing prevalence of the disease.

These links were even found in people with a body mass index of less than 23, i.e. those within the healthy weight range.

"We found that prolonged sitting time and decreased physical activity levels were positively associated with the prevalence of NAFLD in a large sample. Our findings suggest that both increasing participation in physical activity and reducing sitting time may be independently important in reducing the risk of NAFLD, and underlines the importance of reducing time spent sitting in addition to promoting physical activity," the researchers said.

Commenting on the findings, Prof Michael Trenell of Newcastle University, who is an expert on metabolism and lifestyle medicine, said that these findings ‘add to the strong and alarming evidence that sitting too much and moving too little has significant negative consequences for cardio-metabolic health'.

"The message is clear, our chairs are slowly but surely killing us. Our body is designed to move and it is not surprising that sedentary behavior, characterised by low muscle activity, has a direct impact on physiology. With a dearth of approved drug therapies for NAFLD, lifestyle changes remain the cornerstone of clinical care. The challenge for us now is to ‘stand up' and move for NAFLD, both physically and metaphorically," Prof Trenell added.

Details of these findings are published in the Journal of Hepatology.