According to what i've read of the book, you can adjust your schedule on the weekends.

So if you have breakfast at 9:30, have a snack at 12:30, a late lunch at 3:30, then a before-dinner snack at 6:30, then a late dinner at 9:30. You can eat your after-dinner treat as a dessert or right before bed (you probably stay up later on the weekends anyway).

Good luck!