Hypothalamic obesity refers to obesity that is caused by physical or inborn damage to the hypothalamus. The hypothalamus is part of the brain that makes hormones that control specific body functions such as sleep, body temperature, and hunger. It also makes hormones that control other organs in the body, especially the pituitary gland. The symptoms of Hypothalamic obesity vary by the cause and include uncontrollable hunger, rapid, excessive weight gain, and a low metabolic rate. If the pituitary gland is involved, symptoms may include small underdeveloped testes in males and delayed puberty. This condition most often occurs because of injury to the hypothalamus due to a tumor, swelling in the brain, brain surgery, or head trauma. The diagnosis is made by physical examination and review of the symptoms.