I have, the longest time I have gone without food is 21 days. And right here, I have to add that I would never do that again. It shot my metabolism to bits. I apparently did not start eating again slowly enough.
I had a terrible miscarriage, and I did it to heal. It was a time I needed to get close to my Father- He is always at the same place, but we get futher away, and don't hear. Fasting helped me to really listen and ignore the distractions. It was also a time to detox 31something years of toxins. Afterwards I felt like I had shaved 4 years off my age.
So it was never foreign or strange to me.
At the moment I am following the alternate day diet, where you eat about 2000cal one day and the next a 'fast' of about 500cal. I don't eat at all, it is easier to just not eat on down days. So I fast every other day.
And it works for me.