I knew mentioning chocolate would get ya!

I have a nagging question that I can't seem to find an answer for. I'm finding that if I eat correct LC meals for several days and take a small shot or two of chocolate once every few days (like the little miniatures or a two Rollos), I drop 4-5 lbs the very next day. And I don't gain it back. Does anyone have any info or a link to somewhere what will tell me in LC diet terms what is happening? I weighed 198 on Monday of this week and this morning (Wednesday), I weighed in for our contest at 194. That's 5 lbs in 2 days. I had chocolate last night. This has happened to me two other times. Bizarre