Kally - I wouldn't fret about .8 of a lb!! Could be anything from some extra water - to the clothes you're wearing!
I don't have any noticeable "pattern" yet as I've only been doing core for 6 weeks so far! I do notice that around TOM weight loss might be slower or NON-EXISTANT!
Frouf

P.S. For future reference you might wish to post questions/problems on the Main chat/support thread as you are assured of a quicker response!