It is well known that those with hypothyroidism have poor tolerance to cold weather. The thyroid is heavily involved in metabolism and acts as a sort of thermostat for the body. When it becomes dysfunctional, it gets worse at regulating temperature and does not handle cold weather as well. Common advice is to avoid the cold. Is it possible that cold exposure is exactly what we should be doing? If we progressively improve the body’s tolerance to cold, can we influence the thyroid?