A new report shows the global cost of obesity has risen to $US2 trillion ($A2.2 trillion) annually - nearly as much as smoking or the combined impact of armed violence, war and terrorism.

The report, released by the McKinsey Global Institute on Thursday, focused on the economics of obesity, putting it among the top three social programs generated by human beings.

It puts its impact at 2.8 per cent of global gross domestic product.

"Obesity isn't just a health issue," one of the report's authors, Richard Dobbs, said in a podcast.

"But it's a major economic and business challenge."

The company says 2.1 billion people - about 30 per cent of the global population - are overweight or obese and that about 15 per cent of health care costs in developed economies are driven by it.

In emerging markets, as countries get richer, the rate of obesity rises to the same level as that found in more developed countries.

The report offers the stark prediction that nearly half of the world's adult population will be overweight or obese by 2030 should present trends continue.

McKinsey says there's no single or simple solution to the problem, but global disagreement on how to move forward is hurting progress.

The analysis is meant to offer a starting point on the elements of a possible strategy.

"We see our work on a potential program to address obesity as the equivalent of the maps used by 16th-century navigators," McKinsey said in its report.

"Some islands were missing and some continents misshapen in these maps, but they were still helpful to the sailors of that era."