The horror period is an expression of your psychologically maintained sense of hunger, i.e. habit.
Seems to be worse if your diet is bad, too. My worst was when I was drinking rather too much and eating a lot of sugar.
It does get better, though. A lot better.
But it's not an exaggeration to say there are a lot of westerners alive today who have no idea what hunger actually feels like.
(It doesn't just feel like intense cravings, and often doesn't feel like that at all.)
I wasn't talking about you. ;)
But I think that must also be rather different from what I've experienced.
I was never afraid, for example, since I could always just start eating again.
A lot of the stuff Hamsun wrote in Hunger is foreign to me, even as a lot makes keen sense.
The delirium side is clearly physiological, for example. I was tripping quite noticeably while I was at my hungriest.
But I didn't experience apathy - just the occasional furious desire to eat, subsiding after a while.