Hunger and hunger pangs disappear by day 3 or 4, and what pain there is almost entirely mental. Lots of people do 7-10 fasts (especially in California), and this experience is quite typical if not universal. Though, perhaps once you get to the point of starvation the experience changes.
I've done a few 5-7 day juice fasts starting at ~600 calories per day--all sugar as fat and protein prevent hunger from subsiding. After the hunger subsides it's easier to taper off entirely. The hard part is dealing with stress. Even though it's common to experience a mental high and to even perform well athletically, the difficulty with stress betrays the fact that your body has declining energy.
I don't do fasts, but I can attest to hunger pains disappearing after a couple of days, and the fact most of it is mental.
I went from a 3000 calorie/day diet to a 1000 calorie/day diet for 8 months several years back. A few years after that, I once went 4 full days without food (it sucked, but I was mentally prepared due to my experience from that 3k to 1k diet change).
The change in energy will mess with your head/body for about a week until you get used to it.
Edit: People keep downvoting the parent, but I'm not sure why, just because the information comes from someone who does "fasts"?
> all sugar as fat and protein prevent hunger from subsiding
I think you've got that inverted.
People easing into intermittent fasting are often recommended they start with keto to get fat-as-fuel adapted and begin their intermittent fasts with a few days of keto for the very reason that it gets through the hunger pangs while still being able to eat, just avoiding carbs.
> starting at ~600 calories per day--all sugar as fat and protein prevent hunger from subsiding. After the hunger subsides it's easier to taper off entirely.
I think that statement was easily misinterpreted.
After not eating you start to feel hungry. After a couple of days, that hunger will fade. Eating fat or protein will satiate that hunger but will sort of reset that timer on the hunger going away entirely.
I think the idea is you do a 7 day fast, eating a small amount of sugar during the first ~3 hungry days.
I think you're talking about two different things.
Fat and protein giving satiation refers to your hunger subsiding because you're full.
Whereas "eating all sugar as fat and protein prevent hunger from subsiding" refers to the phenomenon that when you're starving, you stop feeling hungry despite the fact that you aren't full. Presumably, consuming sugar doesn't interfere with this, while consuming fat or protein does.
I've done a few 5-7 day juice fasts starting at ~600 calories per day--all sugar as fat and protein prevent hunger from subsiding. After the hunger subsides it's easier to taper off entirely. The hard part is dealing with stress. Even though it's common to experience a mental high and to even perform well athletically, the difficulty with stress betrays the fact that your body has declining energy.