Eternal Food

The word אכילה which we commonly refer to when eating food also means to destroy. This is because food is consumed and then ceases to exist. Therefore, one must ensure that eating is done for the sake of serving Hashem, elevating the act into something eternal.

The words אכילה and שתיה bring out this point. The word אכילה can be understood as a combination of אכל י-ה while שתיה as שת י-ה, hinting that one should eat and drink L’shem Shamayim (for the sake of Heaven).