According to Mrs Chang from Sensible Health, once we flush, we tend to get to our "right weight", i.e, if we are thin we put on some weight and if we are overweighed we tend to lose weight.
Apparently the liver controls so many functions in the body that once it is cleaned it helps us to get to our balanced weight.
Visit her web page and learn more about it.
I would not worry, I think you are taking care of yourself and your body is reponding to it.