The thyroid gland affects nearly every organ in your body. The thyroid gland releases hormones that control the rate at which every part of your body works. In other words, your rate of metabolism.
Lack of thyroid hormone results in a slow metabolism. This is known as hypothyroidism or an underactive thyroid. If there is too much thyroid hormone, your metabolism speeds up. This is called hyperthyroidism, or an overactive thyroid.
Common symptoms of hypothyroidism include fatigue, weight gain and feeling cold when others don't. Hypothyroidism is usually treated with a thyroid hormone containing medication. Common symptoms of hyperthyroidism include weight loss, fatigue, rapid heartbeat, or feeling hot when others don't. Treatment involves lowering the amount of thyroid hormone to relieve the symptoms.