Metabolism is a procedure where the food you consume in your body is broken down into energy. This energy is used across your whole body in order to make sure all the systems are performing accurately. Think of your metabolism as a generator where it takes in raw energy and uses it to power the different organs of your body. The thyroid controls your metabolism with a few specific hormones — T4 (thyroxine, which contains four iodine atoms) and T3 (triiodothyronine, which contains three iodide atoms). These two hormones are made by the thyroid and channelise your body cells to consume the appropriate amount of energy as per requirements.

When your thyroid works appropriately, it will keep the right quantity of hormones to keep your metabolism operating at the correct pace. This is all supervised by the pituitary gland which is located in the middle of the skull, beneath your brain, the pituitary gland watches and regulates the number of thyroid hormones in your bloodstream. When a lack or excessive production of hormones is detected by the pituitary gland in your body, it will adjust the doses with its own hormone. This hormone is called thyroid-stimulating hormone (TSH), and it functions to command the body what needs to be fixed to perform all the operations suitably.