Excess Iodine - Helpful?

Just a little background - My brother has hyperthyroidism and so does my dad to a certain degree, both are skinny. I used to be skinny at 6'4 and only 150lbs. Then for the last 2 years I've tried to consume over 6,000 calories a day to gain weight along with lifting weights. I've gained 50lbs, most of it muscle, but I couldn't seen to gain anymore weight. I couldn't eat anymore then that because it was getting too expensive to buy 42,000 calories of healthy food a week. So I did some research on iodine and how your body needs a certain amount of it for your thyroid to function. I decided to take excess iodine (37.5mg per day) and I've noticed that I've gained weight, even though I've been eating less. I feel great and have been getting stronger and stronger every week, what are the negative side effects of excess iodine? I don't feel any and its been about 3 months taking WAY more then the recommended amount.