Lol, stay strong! Normally I gain about 1 - 2 kgs the day after my cheat day (which is normally a Sunday) - but it's not all fat, actually its very little fat, it's mostly water. Your body uses water to store carbohydrates. So as the week goes by and I continue with my low-carb diet and training my body will drop that water weight as it burns through the stored carbs. So I generally use my Sat morning weigh-in sessions as the true norms :)