Cameron Diaz has shared an image of herself without any make-up with her 2.3 million followers.
The Hollywood star has recently published a book on female ageing, The Longevity Book: The Science of Ageing, the Biology of Strength and the Privilege of Time, which looks at how women can improve their health and well-being from their late thirties to mid-life.
'Ageing is a spiritual and an emotional journey, as well as a physical journey,' she said.
'How do you allow yourself to accept it, engage it, and interact with yourself spiritually, emotionally and physically? If you're not ageing there is really only one other alternative and it sucks.'