Esther 5:1,5:4 says that Esther made the first feast on the third day of the fast.
Earlier (4:16), Esther tells Mordechai that she will also fast for three days.
Did she eat at the feast, or was she still fasting?
Alshich (to 5:5-8) says that indeed she didn't eat at the first feast. Among many other things, this explains why the first one is just described as "the party which Esther made" (5:5), while to the second one Achashverosh and Haman came "to drink with Queen Esther" (7:1).
The Maharal in his commentary to Megillas Esther says that Esther only fasted for 70 hours (as opposed to 3 full days, 72 hours), and she actually broke her fast before going to Achashverosh to prepare herself for meeting the king. This is hinted in the verse "גַּם-אֲנִי וְנַעֲרֹתַי, אָצוּם כֵּן; וּבְכֵן אָבוֹא אֶל-הַמֶּלֶךְ" (Esther 4:17) "we will fast כן - "כן is Gematria 70 - Esther was saying that she would fast 70, and with those 70 hours she would come to the King.