Hi Lily

I've done BFL challenges by the book and LC and I usually treat the free day differently with both of them. I could never bring myself to go all out when doing it by the book - just too much damage to have to fix the next week. I used the day to have more calories, because by the book BFL is pretty low cal (remove fat from the equation and calories tend to go down). Doing it LC I used free day as a day to eat when I was hungry and to not have to count anything. No eating 6 meals, no protein requirement, usually some baked LC cheesecake. Kind of a mental rest, no calculating. Calories on LC free day tended to be lower because of it - LC BFL tends to be higher calorie during the week for me, though.

If you were to have a huge carb blow out that day you'd probably feel really ill afterward, it might interfere with how you performed the next few days. However, if you borrowed from the CKD carb up foods list you might not fair so badly - but that would mean planning and limiting fat and that's not really a free day, now is it?

HTH
-Nat