What are the effects of cheating?

I fasted on Yom Kippur (Friday sundown to Saturday sundown). So for
dinner Saturday night I broke the fast with several dishes I have
become accustomed to using for this purpose.

Most of the dishes were fine on the South Beach Diet, but one
consisted of boiled potatoes topped with (low-fat) sour cream. I
didn't want to skip the dish, as it has become "traditional" for me.

So my question relates to the physiological effects of eating these
potatoes, the first ones I've had since last December. My
understanding is that eating the potatoes causes a spike in blood
sugar, leading to hunger (appetite).

How long does this hunger last? Assuming I did not overeat after my
break-fast (it was a large meal), have I done myself any harm?