2016 Gary Gershoff
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Gigi Hadid revealed Wednesday that she has Hashimoto’s disease, an autoimmune disorder that attacks the thyroid gland.

The model is one of several celebrities — including Zoe SaldanaGina Rodriguez andVictoria Justice — who have opened up about dealing with the disease.

The autoimmune disease sounds severe, but Hashimoto’s is a common, manageable disease according to Dr. Terry Davies, a professor of medicine and director of the division of endocrinology at Mount Siani hospital in New York City.

“Hashimoto’s is inflammation of the thyroid gland, and it’s a very common disease,” Dr. Davies explains. “It comes in mild and more severe forms, and it’s an autoimmune disease.”

While Hadid said that Hashimoto’s caused her weight to drop, Dr. Davies says that one of the symptoms is normally weight gain.

“When the thyroid starts to fail — and the thyroid drives everything in the body, there’s nothing that doesn’t need the thyroid hormone — a low thyroid can lead to weight gain usually, can lead to depression, can lead to high cholesterol,” he says. “It’s a very slow onset, and so when the patient comes to the doctor you’re never quite sure when the disease started. It could be a couple years ago, it could be quite recent, as opposed to other diseases where it’s quite sudden.”

Dr. Davies says it’s uncommon, but those with Hashimoto’s could lose weight at the onset of the disease.

“At the beginning of Hashimoto’s, right at the beginning when it’s starting, when the immune system is attacking the thyroid gland, those cells are dying. And sometimes the thyroid cells come rushing out and for a month or two you can actually become overactive,” and lose weight, he says.

In almost all cases, Hashimoto’s disease is incurable, but Dr. Davies says that the out-of-sync hormones are simple to control with calibrated dose of thyroid replacement medicine

“Treatment is very easy,” he says. “You just need to take it in the right dose, and the doctor can measure very, very precisely the right dosage.”