Weighting game

Several months ago, I had done so well. I watched what I ate and lost over 10 pounds. Then the inevitable backslide that so many supposed experts predict (and it burns me up that they were right).

However, I'm not taking this lying down. I have made specific efforts to exercise more and more-regularly. What really gets me is that for some reason, when I do these things, I reliably put on more weight than when I'm inactive, and immediately as well. I went from 215 to 218 pounds in just a few days, after running and lifting weights three or four times per week. This improvement borders on the miraculous for me, and I am discouraged at the Bizarro-world rules that seem to apply.

Is it water weight? Is it (snicker) muscle mass? Is it an increase in appetite or entitlement due to increase activity that causes me to eat more?

I don't know, but I know I don't like it. I know damned well that exercise provides a multitude of benefits, and that I'd be a fool to let weight fluctuations put me off. So, I won't.But still, it's troubling...