But I feel like it taught me to be bored with eating, and to establish a more healthy relationship with food. High-fat, mid-protein, low-carb sounds terrific for the first day or two but once you're two weeks in, you're so sick of it all that you'd just as soon drink some water and get back to whatever you're doing.
Also if I don’t eat right as I feel hungry I’ll feel as if someone has gut punched me. I get absurdly hungry.
As for the "gut punch" though, sounds like gastritis or something. Unless you're being metaphorical. For me, water helps when I'm fasting and stomach pains start.
Likewise, I've noticed an effect develop with artificial sweeteners where I can have small amounts without difficulty, but if I start consuming it several times in a 48 hour span, I get cramps.
In periods where I've become addicted to carbs hunger pain is much stronger, but I've been able to keep it down for many years now. So if you're getting it intensely, your gut is probably still reactivating to its old profile.
I believe restriction in the regular diet is one way of correcting it while staying in a routine. But I have also experimented with fasting, intense exercise, hot/cold contrast in the shower, and breathing exercises, and the common theme to each is to challenge homeostasis in some fashion. Obviously there's always some danger in going too far, but if our norm is total comfort, we can definitely drop some aspect of it from time to time.
Part of that might be from less water retention early on.
Your body holds on to more water when your diet is full of carbs. As your liver runs down its glycogen stores and you eventually go into ketosis, you lose a lot of water. That's also there the early 'keto flu' comes from, which is a bit like a hangover; plenty of fluids and electrolytes fix you.
Losing water looks great on the scale. On the one hand, it doesn't actually do anything for you healthwise. On the other hand, losing that water ain't bad for your health either (assuming enough fluids and electrolytes), and is a great motivator for the kickstart you described.