Such a bold look! While at the event, Upton talked to ET about body image, and the controversy over some models being deemed "too skinny."
"I think it's all about a woman who's healthy,"she said. "There are women who have curvy bodies, naturally skinny bodies, as long as they're not depriving themselves and living a healthy lifestyle, I don't see the problem with admiring women's natural shapes."
While comfortable in her own skin, and unafraid to try very daring looks, Upton revealed to Details magazine in August that she shies away from going fully nude in her shoots.
"For me those [nude] photos are art," she said. "Your body is art, your body is beautiful, and to be photographed in that way is amazing and it’s received in a very positive way. But with social media and the Internet and not so great blogs and the attention like that, I don't think that my pictures would be received in the way that I'd want them to be received. That's why I've stayed away from them."
And while Kate is often praised for her healthy figure, she admitted in April that she does, at times, feel insecure in the way she looks.
"Every person has insecurities," she said. "But this is the body I was given, I appreciate it and I try to take care of it every day as best I can, but I always enjoy my life. So I'm not going to let my insecurities stop me from enjoying life."