How Jessica Biel Keeps Justin Timberlake

Jessica Biel has revealed that she keeps in shape by following a strict diet when she's working.

The 28-year-old told Glamour Magazine: "When I'm working I'm very strict. If I sugar crash in the middle of a 14 hour day, I'm done for. In that working environment I won't eat bread, dairy, sugar, salt and not a lot of meat."

The actress who is known for her curvy figure also complements her strict diet by doing lots of exercise and strength training.

"I have an amazing trainer, Jason Walsh, who I work with two or three times a week. We do lots of circuit and strength training, especially for my legs and back because it's quite weak from years of gymnastics. I concentrate on making everything strong, and you can't do that with just cardio. I strength-train one day, and I'm not talking heavy weights, just a little," she said.

Super fit Jessica, who is dating Justin Timberlake, admits that even when she's working she relaxes more at the weekends, saying: "When I'm working and I eat healthily all week, I then give myself one day - usually Sunday - when I just eat what I want. You have to, otherwise your mind goes a little nutso."