I can't answer why, but me too.
I went from 218 to 146 - size 16 to a loose 6 in 2008 only to go back up to 189 at the end of 2009, a year and a half at a size 6 which I had never been in my life and I ate my way through some brutal stress and here I am again fighting with myself to lose it........I can see gaining 5, 10, 15 pounds but 45???? What was I thinking????
Live and learn I suppose, here's hoping this is our last time!!!