Just after anecdotal opinions - I have been to the doc and am waiting (and waiting and waiting) for blood test results
(A) I have gained weight despite no change in diet. Not that much, maybe a stone (scales broke and I didn't replace, so haven't weighed in months). I was a healthy weight before and still am, but clothes that used to fit now don't, and clothes that used to be loose are now snug. Gain seems to have plateaued, partly because:
(B) my appetite has gone weird. I don't really get hungry. I get the odd pang, but feel full after eating not very much.
(C) my hair is thinning
. Not falling out in chunks or anything, but it seems to come out easily, and looks sad and flat. I also realised recently that I haven't needed to pluck my eyebrows in ages, whereas this used to be a regular duty. Eyebrows also look thin and need shading with a pencil. Never thought I'd miss my little monobrow 
(D) general sluggish feeling, lack of energy and motivation. Fogged thinking.
I initially assumed it was iron deficiency, but Dr also mentioned thyroid. Having looked up the symptoms I can see I have some of them.
If it is this, can it be "cured" or is it a case of managing symptoms for the rest of my life? If the cause is iodine deficiency presumably I can just take supplements?