5 reasons you need to work on your iodine levels. Iodine deficiency can cause a host of symptoms like * Goiters, which is when the thyroid glands get puffed up, large, or swollen on the front of the neck due to deficiency in iodine * Hypothyroidism. Iodine helps thyroid function, and iodine deficiency causes your thyroid to make lesser metabolic hormones, leading to muscle weakness, weight gain, constipation, cold sensitivity, and other health conditions. * Weight Gain. Iodine deficiency will sl