The global cost of obesity outweighs that of alcoholism, drug use or road accidents and closely rivals that of armed conflict and smoking, according to a new study.

The cost of obesity is estimated at $2 trillion - equivalent to 2.8 per cent of the world’s economic output, the study found. This makes it one of the top three global social burdens behind smoking and armed violence, war and terrorism..

The research, which was carried out by consultancy firm McKinsey, reveals that obesity is now responsible for about 5 per cent of all deaths a year worldwide.

More than 2.1 billion people - equivalent to nearly 30 per cent of the global population- are overweight or obese. That is almost two and a half times the number of adults and children who are undernourished.

A number of studies conducted in Ireland show that two out of three Irish adults, and one in four primary school children, are overweight or obese.

“Obesity is a major global economic problem caused by a multitude of factors. Today obesity is jostling with armed conflict and smoking in terms of having the greatest human-generated global economic impact,” the report said.

McKinsey warned that the situation is worsening with almost half of the world’s adult population forecast to be overweight or obese by 2030.

“The toll of obesity on healthcare systems alone is between 2 per cent and 7 per cent of all healthcare spending in developed countries. That does not include the large cost of treating associated diseases, which take the healthcare toll up to 20 per cent by some estimates. There is growing evidence too that the productivity of employees is being undermined by obesity, compromising the competitiveness of companies,” the study authors said.

McKinsey’s report warns that education and personal responsibility are critical elements of any programme to reduce obesity but adds that additional interventions are also required.

It recommends a number of measures to help combat obesity. These include introducing healthy meals at school and in the workplace, adding more physical exercise classes to school curriculums, including portion control information to products and investing in education for parents and guardians.