I've noticed over the past few years that when I have what is for me a heavy activity day (quiet a bit of aerobic exercise or other activity, to where your muscles hurt a little in the evening from greater use)... or for that matter when I've had to be out in very hot weather... that my weight will trend up two to five pounds in the next couple days... and that extra weight doesn't necessarily go away right away.

Does this happen to anyone else? Theories on why and good approaches to preventing?

For clarification, I have a good water intake and am not taking in more water than usual nor eating any differently or more than usual. I have a scale that measures, to a degree, body water and body fat percentages, and am not seeing a change in those per se.

One thing I've wondered is if my body just has a tough time disposing of cellular wastes and whether stress and extra activity create a backup of some sort. Which makes me wonder what would help besides plenty of water, something like rebounding or similar *light activity* to help lymph, etc. ... and I wonder if anything like more antioxidants would be of use.

(Another possibility is that... as I take thyroid hormone... the extra activity might raise my own thyroid activity and make my thyroid balance a bit on the hyper side temporarily... and one can gain weight with hyperthyroidism as well as hypothyroidism.. although I realize now I don't know the mechanisms by which hyperthyroidism can pack on more pounds, absent eating-related matters.)

I gain a few pounds when the weather is very hot. It is natural to try and retain water then for internal cooling. It goes away again when the weather cools.

I also retain water when it is very hot. This is normal.

Yes Yes YES !

Here I am thinking Im the only person on this big ol earth of ours that STOPS LOSING WEIGHT when exercise increases

If I do anything but walk, you can bet my numblers will come to a screeching skidding halt .. totally bummed out .. but happened too many times for it not to be consistent.

Still not sure why.. I bulk up easily but not THAT easily .. and my body looks different / tighter etc.. but its a real bummer when the scales wont cooperate.

Good luck to you .. The Euphoric highs are only fwapped by the manic lows in this endeavor.