Actress Kate Winslet plans to sue the weekly magazine Grazia over claims she visited a diet doctor in California.
The magazine claimed she had been to the Chinese Healing Institute in Santa Monica to help with neck pain, and also to lose weight.
The 32-year-old Hollywood star told BBC Radio 1's Newsbeat: "I'm very upset, it's categorically untrue, it's a complete lie."
A Grazia spokeswoman said the matter was being dealt with by its lawyers.
"I don't want people thinking that I would ever go to a diet doctor. I never have done, and I never will," Winslet told Radio 1.
"I know I am a role model to young women, it's a role I take very very seriously. I would never want anyone to think I was a hypocrite in doing something like going to a diet doctor," she added.
Winslet's agent, Sarah Keene, said the actress met the doctor "several years ago" for a "completely separate issue".
She told BBC News that Winslet "feels very strongly that curves are fine".
"Women should believe in themselves and not feel pushed to be stick thin," she added.
"She's fine and she's happy with the the way she looks."
Winslet, who has been nominated for an Oscar for her role in the film Little Children, recently criticised the so-called "size zero" culture in the fashion industry.
In December she said she refused to have magazines in her house because of the damaging effect it could have on her six-year-old daughter, Mia.