Not sure if I need more calories, but I certainly feel voracious hunger and cravings the day before and through the first day. Usually by day 2 I'm back to normal. I've only noticed it because the other ~26 days of the month aren't this way at all. It can sometimes make me feel "weak-willed," but I realize it is hormones, then choose to eat something filling and nutritious. Then I choose to eat a single serving of very good dark chocolate