Yep. One word for you: cortisol. It's known as the "stress hormone" and, while I am not sure of the exact biological mechanisms, it is directly linked to weight gain (or slowing weight loss). It's also at least part of the reason that lack of sleep hampers weight loss as well; sleep deprivation causes increased production of cortisol.
"If you drop an egg, you don't say, 'Oh, shoot' and drop the other 11, do you?"
-Source unknown, but obviously brilliant
Reached goal 4/16/2010...but kind of afraid to look these days