Model Gigi Hadid has spoken out about coping with an autoimmune disease .

“My metabolism actually changed like crazy this year. I have Hashimoto’s disease. It’s a thyroid disease,” Hadid told Elle.

“It’s now been two years since taking the medication for it, so for the (Victoria’s Secret) show I didn’t want to lose any more weight,” she added. “I just want to have muscles in the right place, and if my butt can get a little perkier, then that’s good.”

Hashimoto’s is an autoimmune disease where the immune system attacks the body’s own tissues. It can cause fatigue, depression and weight gain when the metabolism is slowed down. Hormones used in treatments can subsequently cause weight loss.

The 21-year-old model recently won international model of the year at The Fashion Awards. The Dazed cover star delivered an emotional speech where she thanked audience members Carine Roitfeld, Bruce Weber and Anna Wintour for believing in her. She added that she worked in the “best industry in the world”.