Erev Yom Kippur
(Excerpted from The Book of Our Heritage by Rabbi Eliyahu Kitov)
It's a mitzvah to eat and drink heartily on Erev Yom Kippur. ...all who eat and drink on the 9th, and fast on the 10th, are considered by Scripture as if they had fasted on both the 9th and the 10th.
The reason why eating on the ninth is considered so great a deed that it is equivalent to having fasted, is that by doing so, we show our joy that the time for our atonement has arrived; ...since we cannot partake of a festive meal on Yom Kippur, we do so on Erev Yom Kippur instead; ...[it] provides us with the physical strength needed on Yom Kippur to focus ourselves on prayer, supplication and reflection that will lead us to teshuvah.
...Although it is a great mitzvah to eat heartily on Erev Yom Kippur, one should be careful to eat only those foods that are easy to digest....
(See further The Mitzva to Eat on Erev Yom Kippur.)
Rav Yehudah Richter says if we eat well (what is good for us and in proper amounts) and with proper intention and say all the brachot correctly and with intent, we can thereby make a tikun for all the sins we made with regard to eating for the entire past year.
Please forgive me for any offense I've given to you over the past year. I promise it was purely unintentional and I'll try to do a better job this year.
G'mar chatimah tovah and Chag Sameach!