Renee Zellweger said eating pizza made her breasts grow bigger.
The star of Bridget Jones's Diary put on two stone for the film.
The American actress needed to put on weight as well as learn an English accent for the role.
She said: "My boobs got lovely and massive. I went up several sizes. I was buying take-out pizza every day and I reckon that helped them grow.
"The difficult thing has been weaning myself off the pizzas. I think I became addicted."
Renee has now gone back to seven-and-a-half stone.
She also took up herbal cigarettes because Bridget is always smoking.
"Even though Bridget does drink and smoke a lot, I don't think it sets a bad example because she doesn't make it look glamorous," she said.