Fat is becoming a weighty economic issue. Almost a third of the world’s population is overweight or obese, levying an economic cost that rivals that of armed conflict or smoking, according to research by McKinsey consultants.

The strain on healthcare budgets is set to mount because unless current trends are curbed, half the global adult population will be overweight in 15 years’ time. In a 150-page report, published on Thursday, the consultants put the global annual cost of obesity at $2tn – equivalent to 2.8 per cent of the world’s economic output.

The estimate is based on loss of economic productivity, costs to healthcare systems and investment required to mitigate the impact of obesity. The cost to the world economy of armed conflict, war and terrorism is $2.1tn, similar to that levied by smoking.