Kristen Bell keeps in shape by eating "colourful" food.

The actress is slim and toned, but admits she struggles to stay in shape. She doesn't enjoy working out and prefers to keep her weight down by eating healthily, something her parents instilled in her when she was a child.

"My mom taught me at a very young age to have a colourful plate. The more colour you are eating, the more vitamins you are getting," she explained. "If you pay attention to what you are eating you will, in most cases, lose weight.

"We live in a world of such immediate gratification that everybody wants that quick fix, or that juice, or that diet. That's not the way it is."

Kristen admits there is pressure on her to look a certain way because of her job. She doesn't pay attention to it, and thinks it's unhealthy to insist all women look the same.

"I've chosen to ignore it. I realised how much of a joke it was when I was criticised when I was pictured on a beach once," she told Look magazine. "All girls sometimes feel like they have horrible bodies and sometimes like we have great bodies."