I too am a male, though in my late thirties. Ive experienced identical symptoms as you have.
I do take, 50mgs of zinc picolinate and let me tell you it works wonders. I also take a copper supplement (2mg). Both of which work amazingly well for libido and getting the "pitcher on bat".
Needless to say, i have experimented with Iodine 5-300mgs at a time for the past 3 years, and i have had a lot of very good things happen on it, while taking all the cofactors. Vision, energy, focus, better body heat, stable mood, I now tan vs burn in the sun, better skin, hair growth (on head). The downside, is basically my penis does not respond anywhere close to what it normally does. The other downside, is i get totally wasted off very little alcohol. I suspect Iodine is impeding my liver function.
I did seem to gain weight like you did too.
When i stop, all goes back to normal while still taking zinc and copper ( I cant say this enough which work miracles in this department). actually my libido is super high due to these supplements. I can also consume alcohol and not feel drunk off 2-3 pints.
Also, I am the lightest ive weighed in 10 years.
Lately Ive scaled back my intake. I just took 50mgs today, but i may take it once every couple weeks now.
Maybe i am Iodine sufficient, im not sure, but high supplementation seems to not be for me. i do however benefit from some.
It's just my personal opinion, but i think extreme doses of iodine may be needed in some cases, cancer patients and those seriously deficient. But for others, maybe we only mild amounts to have things function properly.
BTW what were your symptoms that made you start iodine in the first place?