Why Fat Migrates To Your Middle
Tufts University Health & Nutrition Letter, September 2000

Researchers at the University of Goteborg in Sweden found that monkeys stressed by social disruptions, like overcrowding, were found to have increased cortisol levels. Many of them ended up overeating...and went on to develop abdominal obesity.

As for humans, all that has been found is a rough link between fat stores in the abdomen and higher cortisol levels. It is not clear whether the cortisol levels induced the laying down of abdominal fat or whether the greater levels of abdominal fat caused the rise in cortisol levels, or whether the two had anything to do with each other at all.