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Your Thyroid and How It Affects Your Weight

If your thyroid gland isn’t functioning properly, it can trigger unexpected weight loss or weight gain accompanied by health problems that may require medical attention. Although it’s one of the smallest glands in the human body, the thyroid gland and weight disorders play an important role in your health.

What is the Thyroid Gland?

Your thyroid gland is located in the front of your neck, just below your larynx and Adam’s apple. It’s a small, two-inch, butterfly-shaped gland made up of two lobes, one on each side of your windpipe. This small gland produces important hormones that control the speed of your metabolism which regulates your weight, energy levels, body temperatures, heart rate and many other body functions. Thyroid disorders can disrupt the normal production of thyroid hormones resulting in levels that are too low or too high. If this happens, you can experience a wide range of symptoms, but the most common ones are weight loss (hyperthyroidism) or weight gain (hypothyroidism).

thyroid gland


Hyperthyroidism, caused by an overactive thyroid, makes your thyroid gland produce too much of the thyroid hormone, thyroxine, which accelerates your body’s metabolism. The result is sudden weight loss, even when your appetite and the type and amount of food you eat remains the same. Although sudden weight loss is the main symptom, it’s often accompanied by a variety of other symptoms.

  • Increased appetite
  • Sweating
  • Anxiety
  • Rapid heartbeat
  • Trembling in hands and fingers
  • Sleeping difficulties
  • Fatigue and muscle weakness
  • Bowel changes
  • Hair loss

Hyperthyroidism puts your body’s metabolism into overdrive. You can experience an increased appetite and feeling of extreme hunger, and even though you may eat constantly, you can easily lose 5 to 10 pounds, or more. With increased body temperature and frequent sweating, you’re likely to feel very thirsty and have a need to continually replenish fluids, but this will not affect weight loss.


Hyperthyroidism is more common in women than men, and a family history of the disorder can raise your risk. A simple blood test that measures the levels of thyroxine and TSH in your blood can confirm a diagnosis of hyperthyroidism. In women over 50, these blood tests are especially important, since many older women don’t have the classic symptoms of this disorder.


Hypothyroidism, caused by an underactive thyroid, occurs when your thyroid does not produce enough thyroid hormones to properly regulate your body’s metabolism. The result is weight gain, even when your eating habits remain the same. Hypothyroidism usually occurs at a slower rate over time. At first, you may notice unexplained weight gain and fatigue, but as your metabolism continues to slow down, you may notice more obvious signs and symptoms of the disorder.

  • Increased fatigue
  • Muscle weakness
  • Joint pain
  • Slow heart rate
  • Elevated cholesterol levels
  • Depression
  • Impaired memory
  • Constipation
  • Hair loss

Typically, the more severe the hypothyroidism, the greater the weight gain. In general, 5 to 10 pounds of extra weight may be attributed to the thyroid disorder, but massive weight gain is rarely caused by hypothyroidism alone. If weight gain is the only symptom, hypothyroidism is probably not the only cause since this disorder is typically accompanied by some the the associated symptoms listed above.


Hypothyroidism most often affects middle-aged women, especially over 60. The same blood test used to diagnose hyperthyroidism can also diagnose hypothyroidism. If hypothyroidism symptoms become more severe, they can lead to an enlarged thyroid (goiter), impaired mental abilities and increased depression. Although advanced hypothyroidism (myxedema) is rare, it can have life-threatening complications such as decreased breathing, low blood pressure, low body temperature and coma.