Mine worked like clockwork too. Every 26-27 days, biggest losses the week before TOM. 4 to 7 lb water gain 2 days before that leaves 2 days after it ends. Cue whoosh back down to where I was on the scale. A few weeks of maintenance, rinse and repeat. You could set your watch by it. This is my first month on BC, so everything's behaving differently, in fact I actually feel better! No side effects

I'm sure after a 3-6 month adjustment everything will fall into a different pattern. Certainly beats the 9 month TOM I had after the Depo shot! Took me over a year to go back to normal after that. But when things are normal, it completely goes by a pattern, and the water weight affects the scale measurements very predictably.