Taking together the costs of healthcare, of lost productivity and other spending needed to mitigate its impact, consulting firm McKinsey reckons the annual cost of obesity fat now tops $2 trillion, or 2.8% of global economic output. That compares with an estimate of $2.1 trillion for war and terrorism, and for smoking, and is way ahead of alcoholism ($1.4 trillion), illiteracy ($1.3 trillion) and even climate change ($1.0 trillion).

The report is the latest evidence of the spiralling costs of unhealthy lifestyles that combine low levels of exercise (often due to desk-based jobs) with a taste for fatty and sugary foods. And while the problem may have originated in the U.S. and other rich economies, it is now firmly entrenched and growing fast in many countries that are, by most standards, still poor.

The U.N.’s World Health Organization estimates that over one in three adults was overweight in 208, while more than one in 10 was obese. Twice as many people worldwide live in countries where more die from being too fat than from being undernourished. The most frequent causes of death include heart disease and type-2 diabetes. McKinsey estimates that almost half the world’s adult population could be obese or overweight by 2030 if current trends continue.

McKinsey looked at 74 types of ‘intervention’ that could help reverse a rising trend, ranging from public education programs for parents and children, to workplace wellness schemes and reduced portion sizes at fast food restaurants. Almost all of them deliver far more in benefits than they would cost to implement, McKinsey claims, although it stresses that there is no single “silver bullet.”

McKinsey took the U.K. as a typical case of a developed country with a rising obesity problem. At present, the country invests less than $1 billion a year on programs preventing obesity–only 1% of the total social cost of the problem.

The consultants said that if the U.K. could roll back obesity to 1993 levels, its stretched National Health Service could save $1.2 billion.