Wedding photography is a very physical job, as well as taking a great deal of focus and concentration, so it's really important to have a chance to take a break. In my experience the best time to take a break is during the meal as that's when you're least likely to want to have your photo taken.
As I'm already loaded up with heavy bags and have often been on the go for several hours by the time this opportunity for a break comes along, it's simply not always possible for me to bring food to a wedding (some venues have policies against it too) so I ask that you provide me with at least one meal during a full day booking. It might be what you're eating, could be something from the bar, sandwich and chips... just something to help me refuel and be at my best for the rest of your day. If a meal cannot be provided I may need to go off-site to find an alternative.
Some couples choose to seat me with guests, which has the advantage that I will be in the room and on hand to photograph in-between courses or during dinner if anything happens. If you'd prefer me to eat separately that's no problem at all and I'll happily use the break to review images... but check with your caterer or venue that they can provide a meal while guests are eating so you don't miss out on shots once people are back to chatting and mingling.