Note: The exchange below relates to the specific circumstances of the questioner, and is presented here for general information. For personal guidance consult your LOR (as they say in the USA).
Dear Rabbi Simon,
As you may remember I find it so hard to fast that I have to spend all of Yom Kippur in bed to prevent myself from fainting. Normally on Tisha B’Av I try to fast until Halachic Midday (this is still a struggle but I usually manage it). Should I also do that this year  even though the Fast is postponed?
Also, when I do eat and drink can I eat normally and whatever I choose?
Many thanks for your wisdom and guidance.
Since the fast is “pushed off” to Sunday, you may eat and drink even in the morning, once you feel the need to do so. You do not have to eat minimal amounts, however you should not eat foods which are indulgent or which you would describe as your favourites. And of course wine (and meat—for one so inclined) is off the menu. Before you eat, recite Havdalah on a “popular beverage” such as beer, coffee or tea. I would also allow Coca Cola or similar.
I hope this is helpful.
Rabbi Rashi Simon