Siman 157

It is forbidden to eat and drink in the manner of a glutton and a drunkard, as it is said: "This son of ours is a glutton and a drunkard." The Rambam considers this a complete negative commandment in the enumeration of the mitzvot, siman 195. Rather, one should eat with derech eretz, and one should not eat in the marketplace nor while standing. This will be further explained in siman 170 with the help of Heaven.

The fourth hour from the time one rises from his bed is the time for a meal for every person. And if he is a talmid chacham and is occupied with his study, in order that he not be nullified from his study, he should wait until the sixth hour, and eat at its beginning or at its end, as I have written in Choshen Mishpat siman 5 section 11, see there. And he should not delay further, for it is like throwing a stone into a leather bottle if he has not tasted anything in the morning. (See Magen Avraham that one should relieve oneself before a meal. And if he is unable—he should walk four times ten cubits, or ten times four cubits. And not to prepare a cooked dish from one day to the next, see there. And we are not careful in this. And to prepare something to clean the hands when they touch milk, see there.)