Spending too much time sitting around is linked to about 70,000 deaths a year in the UK, according to public health experts.
Researchers at Queen's University Belfast say treating the consequences of sedentary lifestyles costs the NHS more than £700m a year.
They extrapolated data from previous studies to assess the financial impact of sedentary behaviour.
Lead investigator Leonie Heron from the Centre of Public Health at Queen’s University said: 'We know that spending large parts of the day sitting down increases the risk of a number of illnesses including cardiovascular disease and diabetes.
'This research has enabled us to put a figure on this, demonstrating the huge cost this has on the NHS and highlights the pressing need to address this issue to both reduce the financial cost and improve population health.
'Our research showed that sedentary behaviour contributed to almost 70,000 lives lost in 2016. This could have been avoided if sedentary behaviour was eliminated in the UK.'