Sure, the maze gets boring every so often. And yeah, there's not much variety in the food. But compared to the kill or be killed world of the wild, being a lab rat is a pretty good life. So good, in fact, that researchers at the National Institute on Aging (NIA) believe many lab rats are so overfed they distort research results from experiments intended to help cure everything from cancer to Alzheimer's to, you guessed it, obesity.