AinOhdMilvado,
I definitely believe that the hardship of fasting is 90% in your head.
I can’t vouch for the number, but I definitely agree with what you are saying, at least until the early afternoon. When I consciously fast, I pay more attention to my body’s signals. I may feel equally hungry at 10am on a Shabbos morning as on a fasting morning, but since I “expect” in the back of my mind to eat soon on Shabbos, I tend to ignore or not notice the hunger. That’s why, if for some reason lunch is delayed on Shabbos, the hunger seems to “hit” suddenly.
Anyone else ever feel “thirsty” at Kol Nidrei, even though you just drank a huge amount at the seuda shortly before?