When I was a young whipper-snapper I took part in a thing called a 24-hour famine, where you stop eating for a day in order to raise some money for people who don’t have any choice in the matter.
From what I recall, it was a real struggle. By halfway in I was desperate to eat something, by the end the only thing I could think about was eating.
Only…I’ve just realised, now, that I haven’t eaten for 24 hours. And I didn’t even notice.