Obesity could be socially contagious, according to new research by two of Britain's leading economists. Professor David Blanchflower, who sits on the Bank of England's monetary policy committee, and Professor Andrew Oswald, an expert on the economics of wellbeing, claim that the nation's expanding waistline could be down to people subconsciously trying to 'keep up with the weight of the Joneses'.

After analysing obesity data from the 50s to the present, the pair conclude that obesity may be transmitted across society in a way that is similar to the progress of a virus.

'The starting point for our exploration is the idea that people care about their status and position in society,' the pair write in a research paper for the Economic Research Institute at Warwick University.

They acknowledge that in a Darwinian society, in which people compete for status, being overweight carries a stigma. But as more people become obese the perception of what constitutes being overweight changes. 'Thus when my neighbour gets a little fatter, I ... become a little fatter (since it is now not necessary to be so slim in order to compete),' Blanchflower and Oswald write.

Data suggests that people living in developed countries are approximately 10kg heavier than they were a few decades ago. The two economists found that, among European women, 'there is evidence that perceptions of being overweight depend not just on a person's own Body Mass Index, but also on their BMI relative to other people'.

Their findings are supported by similar socio-economic analyses. Studies have suggested that it is psychologically preferable to be jobless in areas where there is significant unemployment. 'This is presumably for reasons of reduced stigma,' Blanchflower and Oswald write. 'For equivalent reasons, it may be easier to be fat in a society that is fat.' The pair believe that their work could help explain the phenomenon of dieting. They claim that, as people become fatter, slimmer people's status increases, so they choose to diet 'in the face of societal gluttony'. They also suggest an individual's perception of whether they are overweight depends on their socio-economic characteristics and that 'highly educated people hold themselves to a thinner standard'.

Blanchflower and Oswald found that, in the sample of nearly 30,000 people across 29 countries, 31 per cent of men and 43 per cent of women said that their weight was too high.