Office Etiquette — Why Is My Lunch Always Interrupted?

My routine over the years is to grab some take-out or fast food at lunch time, and eat at my desk while continuing to do work.  This just doesn't work.  

First of all, my timing is always bad.  As I bite into the turkey sandwich, someone walks into my office as says "sorry to interrupt your lunch, but I have a couple of questions".  Then comes the return phone call I've been waiting for.  It's just not enjoyable and leads to an afternoon of heartburn.  I've decided that it is much better to snack throughout the day.

Maybe an apple at 9;30, some crackers at 11:30, some grapes or a tomato at 1:30.  When I mentioned this routine on our show this morning, Michael Rock and Larry pointed out that a normal person would leave the building or eat lunch in the conference room.  Do they not realize after all this time that I am far from normal?