You just eat twice as much as you normally would on the feeding days. It's easy and exactly what obese people do except they do it every day.

Start by throwing out everything you learned about nutrition from the government.

explain...

The suggested food pyramid suggests mostly grains and carbs, which spike insulin and trigger the satiety response. It's much easier to eat two thousand calories of protein and fat, than two thousand calories if carbs. Also fat is more than twice as dense in calories than carbs.

Combining this with the human body's capacity for adaptation (it becomes gradually easier to eat bigger meals), eating two days worth of calories in even one sitting is not that difficult.

You don't get enough calories to maintain a stable weight. The only reason I can think of why a 21st century human would deliberately starve themselves is weightloss.

Of course you can get enough calories to maintain a stable weight. Some people maintain a morbidly obese weight with no effort.

I'm literally stunned that you couldn't think of religion.

If you were literally stunned you wouldn’t be able to type.

Oh snap, good point. I guess I havent met anybody who fasts for say, Ramadan. I meet plenty of people fasting as part of a diet.