Thursday of last week was a feed day between two fasts, and I absolutely gorged myself, having a huge breakfast and going to an all you can eat buffet. Out of curiosity, I added up my calories and it turned out to be 2000. My TDEE (total daily energy expenditure) is 1800 kcal.
The funny thing is, this way of eating accustoms you to go for foods that are dense in nutrition and as filling as possible (at least if you've started out with the traditional 5:2 allowance of 500 kcal on fast days), your stomach shrinks, and your sense of when you are no longer hungry is sharpened so you don't feel the need to eat until you are full.