This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.
Except in big cities, everything in the towns shut down from 12pm(noon) to
around 3pm. This means markets, banks, basically everything you need.
Restaurants are open, but a big meal is a no-no. I found it was better to buy
food at a super market in the morning and just munch a bit about every 2 hours.
Typical road food was fruit(bananas, nectarines, peaches), cookies, candy bars
In Spain, everything shuts down from 1pm-4pm and dinner is not usually served
until 8:30 or so. In Italy and France, everything shuts down from about 12:30
pm to 4pm and dinner is not usually served till 7pm.