Parathyroid disorders generally do not cause weight gain. Common side effects of parathyroid disorders are loss of energy, kidney stones and depression. Parathyroid glands are responsible for regulating the level of calcium in the body, explains Cleveland Clinic.
There are two parathyroid glands on each side of the thyroid. The parathyroid glands lie directly behind the thyroid gland on the lower front of the neck. While a thyroid disorder typically causes weight gain or loss, parathyroid disorders result in increased or decreased production of a hormone called parathormone. Parathormone plays a role in vitamin D formation, calcium absorption and phosphate excretion, explains MyVits.com.