Jessica Biel's lengthy work-outs

Jessica Biel spends five hours a day exercising.

The Hollywood actress - who is dating 'SexyBack' singer Justin Timberlake - works hard to maintain her svelte figure because she feels under pressure to look good for movie roles.

She said: "I've worked out five hours, sometimes more, in a single day, if I'm in training for a film role or something. And it's hard - it's very hard!"

Despite her gruelling exercise schedule, the 27-year-old beauty has to make sacrifices with food too and often only eats controlled meal portions.

She explained: "You have to find a balance, especially with what you eat. I don't live by the idea that you can't allow yourself a treat.

"I say, 'Eat things you like, but eat them in smaller portions.' I always cut things in half and send half back. I'm not perfect, I don't always do those things, but that's the goal."

"Do I eat dessert? You know, if there's something I want to try then I try it. But I have a bite, not the whole thing. That's what you have to do."