Eating one of the major meals (breakfast, lunch, dinner) should be absolutely forbidden at the keyboard. I am disgusted by people who have that habit at work. You absolutely don't leave plates on your desk afterwards with leftovers of something that smells (shrimp, microwaved meat, ketchup, vinegar, mayonnaise, etc.) !
Snacks that isn't sticky is OK. Coffee (coder-fuel) is encouraged.