The 26-year-old California Gurl says that she had 'enormous boobs' when she was a teenager and wore bras that would minimise the size of her chest.
Perry tells US Elle: 'I was shaped like a square at one time. I was!
'I'm generally around 130lbs [9st 4], which is totally fine for me. But when I was a kid, I was the same height and weighed more like 145lbs [10st 5].
'And I had enormous boobs that I didn't know what to do with, so I wore minimisers, which were not cute.
'Those thick a**-straps! I got made fun of for the over-the-shoulder-boulder-holder...and all I wanted was to look like Kate Moss.
'Little did I know that these things would come in handy some day.'
Raised a strict Christian in Santa Barbara, Perry says that she is now comfortable with her body.
She says: 'I'm a sexy girl, so what? I never claimed I was a nun!'