People can go without food for a lot longer than they can go without water. 20 days is near the upper end, and not something you should do often, but very much within the normal human limit.

EDIT: s/food/water/

Appetite goes away after 48 hours or so, and then it’s easy until appetite or hunger come back, which take 3-40 days depending on your health, fat reserves, etc.

I had lost my appetite that time, so even first two days were easy.

On phone, so hard to google, but there have been a few we’ll documented cases of people going a whole year with just water, vitamins and ridiculously little protein (losing 100-250 pounds of fat in the process).

Also google valter lungo - fasting 2-3 days at a time is very healthy for you.

For onlookers, https://en.m.wikipedia.org/wiki/Angus_Barbieri's_fast

Small typo: Valter Longo, and you can google Fast-Mimicking Diet (FMD). Highly recommended both as stuff to read, or a 5-day fast to try.

Its quite common with prisoners on hunger strikes. Apparently the feeling of hunger stops after a few days. Have to mention that you should be rather careful with that, the long hunger strikes where people died after month were with a forced feeding tube. With 20 days of total starvation you are already up there.

Refeeding is the dangerous bit, I recall reading. Needs medical supervision, at any rate.

A holocaust survivor once told me her mother died after liberation of the camp by English troops, because they started eating the ample supplies that the guards had kept for themselves. Truly tragic.