Most of the times it is noticed that constant blood sugars being out of control has led to other complications viz. Renal, Thyroid, etc. subsequently a cut down on Salt is prescribed or suggested.
Until the USDA food guidelines of 1970s, Iodine was recommended to be eaten as it has many roles to play in the body especially the thyroid hormones for proper bone and brain development. Studies were conducted and children fed with salt daily (which was then fortified with iodine) performed better at exams and had higher IQs then those deficient.
It’s not the salt itself that’s making you gain weight—it’s the fact that most salty foods are processed and contain loads of sugar, gluten and preservatives, as well.