Kate Upton has admitted she got frostbite after posing for Sports Illustrated magazine semi-nude in below freezing temperatures.The curvy 20-year-old model claims her body began shutting down from the cold after a sexy photoshoot in the Antarctic, which saw her cavorting around semi-nude in extreme temperatures of up to -20Â°C for Sports Illustrated's swimsuit issue.She confessed during an appearance on the 'Today' show: "It was freezing. I had frostbite when I came back. I was worried about my body. I was losing hearing and eyesight as my body was working so hard to stay warm. My mum said, 'I told you not to go there.'"My body was shutting down, it was working so hard to keep warm. I could only do 10 frames before I couldn't take it anymore, and everyone came with a blanket or coat and I even got this huge pink sleeping bag to keep me warm. That is the only way I could do it."Kate - who was named one of the sexiest women of the millennium by GQ magazine - has posed for Sports Illustrated a number of times, and the raunchy shoot marked the buxom blonde's second front cover for the infamous swimsuit edition.She said: "Sports Illustrated really launched my career and I have a lot to thank them for."