One of the main complaints of hypothyroidism is fatigue, which is mostly caused by low levels of thyroid hormone but may also be the result of low B vitamin status. (progressivehealth.com)
Lower levels of thyroid hormone means lower energy, and since less calories are burned for energy, more weight is stored. (everlywell.com)
That's why low levels of thyroid hormone cause you to feel colder than others around you. (healthline.com)