Renee Zellweger Packing On Pounds

(AP)  Renee Zellweger says putting on weight for her role in the new "Bridget Jones" film has been a piece of cake - but no doughnuts.

"It's really just math. I've been eating lots of really fattening food. I read that I'd been eating doughnuts, but they're not really my thing," Zellweger said as she braved a rainy London evening Wednesday to attend the premiere of "Down With Love," also starring Ewan McGregor.

Zellweger played a lovesick and slightly overweight Londoner in 2001's "Bridget Jones's Diary," based on the novel by Helen Fielding. The sequel, "Bridget Jones: The Edge of Reason," is scheduled for release next year.

The 34-year-old actress was wrapped warmly in a black wool coat and knee-high black boots to greet fans outside the theater in Kensington, southwest London.

Zellweger said she's been working with a nutritionist who's been feeding her healthy food with hidden fat. Breakfast includes four slices of toast and cream cheese.

"That's just the first course," she said. "It's a four-course breakfast. I don't really think about it because I'm usually doing something else."

Zellweger said she still exercises, but "if you are talking about running in Hyde Park, I'm not going to be doing that."

Asked how she would lose the weight, the answer was again simple: "Just by doing the math."