The obesity epidemic has grown too big to ignore.

A new report by McKinsey estimates that obesity is costing the global economy $2 trillion per year. That makes it nearly as damaging as armed conflict or smoking, according to the consultants.

More than 2 billion people -- or almost 30% of the global population -- are currently considered overweight or obese, and the problem is expected to get worse.

Based on current trends, nearly half of the world's adults will be overweight or obese by 2030.

"Obesity, which should be preventable, is now responsible for about 5% of all deaths worldwide," the report stated.

Smoking is considered the most expensive man-made burden on the economy with a cost of $2.1 trillion, followed closely by armed conflict.

Related: Employers are measuring workers' waistlines

The damage caused by obesity mainly comes from lost productivity due to disability and premature death, and higher healthcare costs.

So what should be done?

Among the options, governments can redesign cities to encourage cycling or subsidize healthy meals in schools. Both would generate a good return on their investment.

But the fast food giants need to play ball too, by changing the menus in their restaurants. That's much easier said than done.

Burger King (BKW) said in August that it was removing its lower-calorie fries from most of its restaurants because the product had proved less popular than it hoped.

Burger King billed the Satisfries as having 40% less fat and 30% fewer calories than McDonald's fries.