Well it does depend on the situation the characters are in. If they are in a suburban home with a grocery store down the street, there's no need to remind the reader that they need to eat while you graze over a few hours or even a day. If they are off in a jungle and are out of rations, however, a main point of the story at that time is to keep them fed and alive. As for going to the bathroom, whether or not the proper facilities are available...your characters can do that at any time anyway. Unless they are locked in a car with a ruthless killer dog waiting outside if they open a door, peeing isn't an issue worth mentioning. Otherwise it is, and adds a touch of realism to a story.
I've noticed that a number of mystery authors choose to entice the readers with some interesting sounding dishes, somewhere in the story. Robert B. Parker, Linda Barnes did more often with her Michael Spraggue character than with Carlotta Carlyle, Sue Grafton does, and so does Patricia Cornwell. To some extent, I believe that is to announce the character's appreciation of the good things in life, but it's also something the readers often look forward to. It's also a way the author shares a little of his or her own other interests with the reader (Patricia Cornwell even published a separate cookbook featuring some of the dishes her Kay Scarpetta character specializes in).
