A number of people have complained about consistently running a low fever with the Mirena-- it seems like something like that could account for you feeling cold. I saw a few people lost weight, though the vast majority gain. I guess fooling with your hormones/metabolism can go either way. Definitely a hormone imbalance accounts for our problems-- seems like it starts with the progesterone but, since you have done research, I'm sure you know that progesterone/estrogen/testosterone are finely tuned/related. I think it all gets out of whack if you are so inclined and have the Mirena long enough. (I had it 4 1/2 years.)