I presented today at a conference where the theme of our section was body weight and economics. I had an interesting conversation with a lady about snacking. She remarked how she grew up in the Middle East, and that her family ate three meals a day but no there was no snacking in between. She remarked that there wasn't any snack food available then as there is today.
I've got a post coming up on snacking, as I think it is a major factor in the obesity epidemic. In my view, a lot of snacking is simply eating in the absence of hunger, and therefore the extra calories from snacking should correlate with weight gain.