LONDON -- Being fat is the new normal, but it won't last. The global surge in overweight people is concentrated among lower-income city-dwellers, and some may choose to slim down as they climb further up the income scale. ("You can never be too rich or too slim.") But the real guarantee of a slimmer world, unfortunately, is climate change.

"Obesity is the norm globally, and under-nutrition, while still important in a few countries and in (certain groups) in many others, is no longer the dominant disease," said Dr. Barry Popkin of the University of North Carolina last week at a conference in Queensland, Australia.

Popkin studies "nutrition transition," the changes that accompany the shift from a traditional rural diet to a modern urban diet, and he has concluded that thanks to high-speed urbanization, the fat now outnumber the starving.