Millions of people are unable to work or are less productive because they are obese, according to a report that suggests the condition helps to explain why economic inactivity rates due to sickness in the UK are at record levels.

The Institute for Public Policy Research, a think-tank, is calling on the government to stop treating obesity as a matter of individual responsibility and to tackle “working conditions, changes in the built environment and our broken food system” to reduce the number who are severely overweight.

The UK has the third-highest proportion of people living with obesity in the OECD, affecting one in four adults. Only the US and Chile have higher levels. The IPPR cited a report from Frontier Economics, a consultancy, which said obesity cost the UK an estimated ￡98bn every year, including through lower productivity.