One estimate from earlier this year found that almost one-third of the world was now obese (that’s more than 2 billion people) and that numbers had been rising, significantly, for decades.

The world’s growing obesity and the health problems that come with it are a big deal — and come with a significant cost.

A new report from consulting firm McKinsey estimates that the world’s obesity problem cost it $2 trillion in 2012. That’s more than alcoholism, climate change, or drug use, and almost as much as war and terrorism or smoking.

McKinsey’s report, titled “How the world could better fight obesity,” hopes to outline the ways that things could improve. It paints a complicated picture, not only calling for better education and personal responsibility, but also further intervention over a variety of sectors to force change.

The problem is that there’s not too much evidence as to what exactly works in the battle against obesity. With no major success stories in combating obesity in the last 30 years, we’re left to guess at what actually works.

MicKensey is aware of these limitations, but hopes that things will evolve, especially given the high financial and human cost of obesity.

“We see our work on a potential program to address obesity as the equivalent of the 16th-century maps used by navigators,” the report notes. “On those maps, some islands were missing and some continents were misshapen, but they were still helpful to the sailors of that era.”