Today I learned, from RadioLab via Andy, that it you are busy thinking too hard (like remembering 7 items instead of 2), it’s hard to choose fruit salad over chocolate cake. Well that explains so much! It’s about the same part of the brain trying to keep things straight.
Here, listen for yourself. It may just make more sense if you hear the whole story.
http://www.wnyc.org/shows/radiolab/episodes/2008/11/14/segments/113274
What’s your excuse? What’s filling your brain? Leave a comment!
Jane's Lessons Learned 
ok, so what I got from this is our brains are too full of facts, so make a choice of knowing the facts only about things you really care about. Sounds too simple. I wish he explained it more. Not sure what to do with this info.
The other part I got is that the brain is anatomically organized into 2 systems at war, competing for attention (emotional push to cake, the other frontal cortex is the rational, reasoning, deliberative system) has too much to keep track of, gets tired and can’t put up a fight, so you choose the emotional pull – cake.
The kidney part was weird…was that part of the same story?