Antonyms for the phrase "filled to overflowing", which means completely full, include phrases like "empty", "barely half full", "scant", "sparse", "depleted", "deficient" and "lacking". These words describe a lack of abundance or a shortage of something rather than a surplus. When we talk about things being empty or devoid, we imply that it is not being used to its full potential. On the other hand, when we concern something lacking or deficient, it implies that it's not adequate or insufficient. These opposite words of "filled to overflowing" are useful when the language requires contrast, balance or emphasis on what is scarce or not available.