There is a complex relationship between the thyroid, body weight and metabolism. The thyroid regulates metabolism and directly influence an individuals weight. It releases hormones that control metabolism—the way your body uses energy. The thyroid is part of the endocrine system, which is made up of glands that produce, store, and release hormones into the bloodstream. The thyroid gland uses iodine from the foods you eat to make two main hormones Triiodothyronine (T3) and Thy