The former Grey's Anatomy star, 36, is known for her gorgeous figure and curves now, but she's revealed back as a 15-year-old she was "super flat chested".
During an appearance on Conan, the beautiful star revealed she was teased by boys at school because of her lack of cleavage, prompting her to pray and pray that she'd develop big boobs at some stage…
"I spent the next, however, many months and years praying and praying and praying to get big boobs, like that's all I wanted. I prayed. I fasted for big boobs," she said.
Katherine continued: "I grew up Mormon and once a month you have a fast and testimony meeting and you're supposed to skip two meals and fast for things that matter. Good health. Safety of the family. World piece. That sort of thing...
"I fasted for big boobs. I cut photos from the Victoria's Secret catalogue of the body I liked and put the head I liked on top of it."
Well, Katherine got her wish… but jokingly revealed a minor issue with her grand plan for an impressive bust…
"The problem is no one warns you that with real larger size breasts comes issues the Victoria's Secret models don't have like gravity, and bigger butts and bigger thighs! So I've had to spend the rest of my life with big boobs trying to make sure everything stays tight and where it is supposed to!"
Conan pointed out that Katherine looked "absolutely fantastic" and didn't need to worry, prompting the starlet to quip: "Because it's all hoisted up!"
As for those boys who used to tease her at school, well… who is having the last laugh now, huh?!
Catch Conan Mon-Thurs at 11pm on truTV in the UK, freeview channel 68
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