It actually depends on which version of the question is being asked, there's a whole thread about that:
http://www.flyertalk.com/forum/trust...bout-food.html

I'd strongly reccomend selecting YES if you get asked the "food" question, but no need to declare it if it's the meat, cheese, fruit, vegetables, etc question. Some agents are reported to get annoyed if you declare chocolate/sweets/etc (for the more generic "food" question), but not declaring it would potentially put you at the risk of losing GE. I'd certainly prefer to be safe rather than sorry.

Note: apparently in the past kiosks gave an X for food declaration, but nowadays they give a circle / O - meaning you might get asked what you're carrying at customs, but you won't have to stop at immigration (of course there are exceptions, e.g. Canada, where everyone goes through immigration regardless of GE).