Hello, It depends on the cause of they hypothyroidism. Mostly, it is due to sluggish thyroid. Making sure there is enough iodine in the diet is essential and often changes thyroid activity to a small but significant degree. Don t use silly high amounts but make certain there is at least 100% of the RDA. Also, the RDA is quite an oversimplification in this particular case because the amount of thyroid hormone varies with stress. Serious illness causes a temporary decrease in thyroid hormone and results in over prescribing of hypothyroid treatment very very commonly. And, changes in thyroid hormone on a moment to moment basis is one way the body regulates temperature ! That s the sum of all the literature on cold and thyroid. Does swimming in a standard 75 degree pool affect thyroid? Does a hypothyroid person get hypothermia more easily (yes, but does a chilly pool cause it in hypothyroid? Who knows but a standard thermometer would find that out). Basically, these are unknown. Does exercise affect thyroid, yes. Does fasting/starvation ? well, yes, but the extent and what to do about it isn t known. Ok, at 60, increasing the body s resilience to stress will, by tautology make the thyroid normalize. This involves standard exercise, good sleep, and I would include exposure to a wide variety of outdoor environments. Oops, nobody knows this yet, I better get writing. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr. Matt Wachsman