User blog comment:Xilinoc/Realistic One Piece/@comment-24850639-20150526201609/@comment-24.235.56.170-20150528024815

I think the combination of her being a teenager at the time and Sanji's magical cooking made her gradual bust enhancement make a certain kind of sense. It doesn't account for everyone else in the grand line/new world, but a growing woman gaining a few cups makes sense is not at all unexpected.

Also, I've always thought that Sanji, perv that he is, discovered some hormone or vitamin or something, that he has been slipping the ladies to make their boobs grow. Certainly puts a whole new spin on why he insisted on all of his drinks and snacks being meant for the girls.