Can Hyperthyroidism Cause Weight Gain?

Hyperthyroidism is generally associated with weight loss due to an overactive thyroid gland increasing metabolism. However, there are certain situations where hyperthyroidism can lead to weight gain:

  1. Increased Appetite: Some individuals with hyperthyroidism experience a significantly increased appetite, which can lead to consuming more calories than are being burned, resulting in weight gain.
  2. Treatment of Hyperthyroidism: When hyperthyroidism is treated, particularly with medications or radioactive iodine therapy that reduce thyroid hormone levels, the body’s metabolism can slow down. If dietary intake is not adjusted accordingly, this can lead to weight gain.
  3. Muscle Mass Loss: In hyperthyroidism, weight loss is often due to muscle mass loss rather than fat loss. Once the hyperthyroidism is treated, the body might regain muscle mass, which can increase overall weight.
  4. Fluid Retention: Certain forms of hyperthyroidism, such as Graves’ disease, can cause fluid retention, contributing to weight gain.

If you have hyperthyroidism and are experiencing unexpected weight gain, it’s important to discuss this with your healthcare provider to understand the underlying cause and receive appropriate guidance.