The thyroid is a butterfly-shaped gland in the neck that produces a hormone that helps to regulate your metabolism. Part of that metabolic influence affects appetite, as well as the way your body extracts energy from the food you eat. The status of your thyroid will directly impact weight gain and loss. When the thyroid is removed in the event of thyroid cancer or an overactive thyroid that cannot be controlled by medication, you must take a medication that replaces the thyroid hormone that is no longer being produced by your thyroid. Weight gain is a common result, but you can lose weight if you're careful about diet, exercise and maintaining the right dose of your thyroid medication.
Metabolism
Understanding how your thyroid works will help you adjust if you must have your thyroid removed. If you suffer from hypothyroidism, or underactive thyroid, you may experience weight gain that is largely due to a buildup of sodium and water. You have a slower metabolism, which also means the calories you consume are not converted to energy efficiently, so you tend to gain weight. Overactive thyroid, or hyperthyroidism, results in a metabolism that requires a greater number of calories to maintain weight. Often, someone with hyperthyroidism doesn't eat more to keep up with that faster metabolism, so weight loss is unavoidable.
Thyroidectomy
Removing the thyroid is done to protect the body, either from a cancer growing in the thyroid gland, or from a hyperactive thyroid that is producing too much thyroid hormone. Hyperthyroidism can be treated with medication, but if your body is resistant or you don't want that treatment, surgery to remove the thyroid is an option. There are risks, as with any surgery, but they include possible damage to the parathyroid glands near the thyroid and that can result in an unhealthy imbalance of calcium and phosphorous in the body.
Post-surgery Treatment
If you have your thyroid surgically removed, a treatment using radioactive iodine, I-131, is often performed to make sure any remaining thyroid tissue is destroyed. However, in order to prepare for the treatment, you must go off your thyroid replacement hormone to raise the amount of thyroid stimulating hormone, which helps in the uptake of radioactive iodine. As a result, you may experience hypothyroidism symptoms, which can include weight gain. You may want to be particularly careful about your calorie intake and activity level during this period.
Warning
Determining the right dose of thyroid medication after your thyroid is removed, or even if you still have your thyroid but you're on medication, can be a challenge for you and your doctor. Lab tests can determine a healthy range of thyroid stimulating hormone in your body at a given time, but other factors will be considered, too. Your doctor will look at whether you have heart palpitations, insomnia and an increased appetite, as these are all signs that your dose is too high. If you're able to lose weight easily and your appetite seems normal, your dose may be just right, but understand that as you age, your TSH levels and other signs may change and your dose may be adjusted many times throughout your life.
Awareness
After you have your thyroid removed, if you experience weight loss without necessarily trying to lose weight through diet and exercise, or you gain weight unexpectedly, tell your doctor, as these could be signs of illnesses unrelated to your thyroid condition. Depression, for example, can lead to both weight gain or weight loss. It's always a good idea to note changes in your mood and physical health and share this information with your doctor.
