Agree with previous ANON-most Americans are deficient in iodine. The body can not absorb iodinee if the receptors are blocked.
Chemicals such as FLUORIDE(you know, the stuff you brush your teeth with!), BROMIDE(in bread), and CHLORINE block receptors in the thyroid. as a result, hormones are out of whack, many gain weight.
Do yourself a favor, the next time you go see your dr, ask for a heavy metal blood test (covered under insurance). Find out where you are on the richter scale. If any heavy metals have a "high" rating, you may want to do a cleanse (I suggest the Master Cleanse). Then start eating organic. God put fruits and veg on the planet for reason. All your nutrients are in there. (Also, there's something to be said for a good ole hamburger now and then!
https://www.hbmag.com/foods-that-block-thyroid-function/