Quick question: the word "γεύμα" can mean "lunch" too, right? (besides just "meal"). If so, is it commonly used that way as an alternative for "μεσημεριανό"? (the latter is much harder to memorize... haha).
In general, Greek uses the definite article much more frequently that English does. Especially in this case (... μετά (από - implied) το μεσημεριανό), the article is indispensable after the preposition.