Lawyers for Catherine Zeta Jones have warned news organisations not to link the actress with the Atkins diet.
Zeta Jones and Douglas won damages from Hello!
Legal action has been threatened against anyone who publishes stories saying the actress is on the diet.
In a letter to international media, Zeta Jones' lawyers said Atkins was "derided by nutritionists and other health care officials".
The diet has become a global phenomenon in recent years with millions of copies of the Atkins book sold.
But the diet has been widely criticised although there has been no medical evidence to support claims it is dangerous.
In the UK, the Food Standards Agency, not mentioning Atkins by name, said that high-fat diets were linked to obesity and were "unpalatable and dull".
An estimated three million people in the UK have tried the Atkins diet.
Atkins spokesman Richard Rothstein told The Smoking Gun website, which focuses on celebrity lawsuits: "It's never been our policy to seek celebrity endorsements.
"Where tabloids get their info is a complete mystery to me."
The lawyers' letter said news reports made it appear that
Zeta Jones was "more concerned about her outward appearance than she is with serious health concerns".
Zeta Jones and her husband Michael Douglas recently won £14,600 in damages from Hello! magazine after it published unauthorised pictures of the couple's New York wedding.
Douglas is in London on Wednesday, signing a £3.3m deal to promote the island of Majorca - where the couple have a home - as a holiday destination.
Meanwhile, British TV star Gail Porter has said she must take medication for the rest of her life because of her battle with anorexia.
The presenter has been left with a thyroid problem after dieting herself for 10 years.
She now has to take pills on a daily basis or risk serious damage to her health.