Jennifer Lopez Marie Claire UK cover 2010 backless dress

J.Lo shows off her back-up plan on British Marie Claire's June cover. Photo courtesy of Marie Claire U.K.

When she first started making her name in Hollywood, people paid more attention to Jennifer Lopez's rear than her career. And all these years later, the entertainer says she still doesn't quite understand all the fuss about her fanny.

"I was always very comfortable with who I was. Confident," Lopez tells the June issue of Marie Claire U.K., on sale Thursday. "I've never looked at myself [my body] in a negative way."

It doesn't hurt that the 40-year-old mother of 2-year-old twins Emme and Max has a body that most twentysomething women would kill for. Though she keeps fit by running and lifting weights, Lopez is much more laidback when it comes to her diet.

"Just like anybody I try to watch what I eat -- there's no big science to it, which is what sucks," "The Back-Up Plan" star tells the magazine. "One of the good tricks is to have a goal -- for me it may be getting in shape for a video shoot.

"The other is portion control. I love to eat everything and you pretty much can -- a little piece of something fattening is not going to kill you. It's when you eat the whole box that it's going to kill you. If you can learn to not eat till your stomach feels full and gross, then you can pretty much control your life in that area."

Jennifer Lopez Marie Claire UK

J.Lo unleashes her inner flasher. Photo courtesy of Marie Claire U.K.

The former Fly Girl feels also tells the Marie Claire U.K. that marriage to singer Marc Anthony has given her a "kind of love with no question mark," and that she's still on cordial terms with former flames Ben Affleck and Sean "Diddy" Combs.

'Would I see a movie of Ben's? Sure! Why not?" she says. "And Sean -- I've run into him once or twice, with Marc, and it's always very friendly."

That diplomatic attitude extends to Lopez's take on younger female chart-toppers like Lady Gaga and Rihanna. "I love them all," she tells Marie Claire U.K. "Honestly."

All, right, all right, but since she's being honest, let's get back to that famous bottom. Is it true it was insured for millions of dollars?

"No!" Lopez clarifies. "Though I thought that story was funny. In fact, we traced that story, and that was a rumor that started in London."

Jennifer Lopez Marie Claire UK

She's come undone: Jennifer Lopez reveals almost all in the new British Marie Claire. Photo courtesy of Marie Claire U.K.

For more of J.Lo in Marie Claire U.K., visit the magazine's Web site.

Find out why all eyes were on J.Lo's hair at the Paris premiere of "The Back-Up Plan."