Gigi Hadid has to work hard to maintain her supermodel figure. The 21-year-old recently opened up to Elle magazine at the Reebok #NeverPerfect panel about a thyroid condition she's silently struggled with for years.

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"My metabolism actually changed like crazy this year. I have Hashimoto's disease," she told the mag. "It's a thyroid disease, and 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, I just want to have muscles in the right place, and if my butt can get a little perkier, then that's good."

To stay in shape, Hadid regularly boxes, saying, "What's great about boxing is that I couldn't come to New York and sign up for Equinox, and go running. It was not good. So, I knew I needed to find something that gave me a coach, gave me a family... so that when I walk in, it's like my big brothers. They're like 'what up!' They don't care about who I am. That's what I needed, and they don't care about what my body looks like. They care that I give a good punch, and that's how I want to be judged. That's what makes me proud of myself."

Model Gigi Hadid presents a creation during the 2016 Victoria's Secret Fashion Show at the Grand Palais in Paris, France, November 30, 2016. (Reuters)

In addition to her intense workout regimen, the supermodel also consumes a healthy diet. She dished on her favorite foods, saying, "I do like eggs, but all different ways. I loved baked eggs. I like tomato and bacon. There's a Middle Eastern spice called, zaatar, so I'll do eggs and zaatar. I love eggs! In general I like fresh ingredients. I'm not a salad and meat type of person; to me, that's boring."

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Hadid also revealed that she's taking a break from social media, calling the move "empowering."