Carbohydrates affect the brain:
http://www.telegraph.co.uk/news/ukne...addictive.html
If anyone wants to research this further just follow "carbohydrate/opioid" etc in the Google search area. There's quite a bit on it which is good, because it saved me having to type it out of a book for a change.
Also see the "Food and Mood handbook" by Amanda Geary.