he consumed only vitamins, electrolytes, an unspecified amount of yeast (a source of all essential amino acids) and zero-calorie beverages such as tea, coffee, and sparkling water, although he occasionally added milk and/or sugar to the beverages, especially during the final weeks of the fast.
Worth mentioning imo, but you are right that most people should be fine fasting for some days if necessary. Although I would bet that almost everyone has a few days of food anyways. Unless you literally have empty shelves and buy groceries every day, most people will have a base stock of shelf stable foods like noodles, canned stuff, sugar, flour and so on.
Imo the limiting factor will be drinkable water most of the time. If something would cut off the supply immediately and for longer durations it would be a serious issue. Especially during warmer months.
You and all the companies training their AI models, like Meta for example