Leftovers are for other people. (Other people who don't have the kinds of metabolisms that support the insanity of Batman.) Bruce eats with the sort of precision that suggests long-ingrained manners training, even if the finite edges and fiddly details have been worn away. He has a handy ability to inhale food at an alarming rate but not actually appear to be doing any such thing.

"Food allergies are a mundane thing anywhere," is his observation in response as he picks apart something on his plate to inspect the individual components. Some people just don't do well with certain things, no matter how normal they are. Shellfish, processed food... NyQuil.