The 20-year-old swimwear model has hit back at critics who pass judgement on her curvaceous figure and insists she is comfortable in her own skin.

Speaking to Vogue magazine, Upton said: ''The things that they're rejecting are things that I can't change. I can't change my bra size. They're natural! I can work out and I can stay healthy and motivated, but I can't change some things.

''I really just live my life. I love my body. It's what God gave me! I feel confident with myself, and if that inspires other women to feel confident with their bodies, great.''

Upton further explained that she's worked really hard to make it into Sports Illustrated, adding: ''I always had career goals. And I figured out a path I wanted to take to accomplish those goals. If that meant calling the best modelling agency in the world, that's what it meant.''