The actress felt no anxiety about appearing naked in several scenes in Lars von Trier's new sci-fi drama and refused to diet or hit the gym to tone up before baring all.
And Dunst is convinced movie audiences will be stunned by just how curvy she is.
She tells Britain's Elle magazine, ""I trusted everyone and the lighting was beautiful. I didn't work out beforehand, it was all very natural.
""I don't have any real body issues. I never really overeat, I shed weight in the summer, put it on in the winter and yes, I do have big boobs. People don't realise because I cover up a lot, but they are there. Big boobs.""