The 39-year-old star's book is aimed young girls and comes after gaining inspiration from her friend Gwyneth Paltrow's weekly lifestyle journal Goop!, which sees the US actress provide wellness tips, recipes and fashion advice.

A publishing source said: "Cameron has become very close to Gwyneth and it's been very interesting for her to see what Gwyneth is doing with Goop!.

"She's been inspired by Gwyneth and the way she uses her fame to influence and help people. Now Cameron wants to do the same."

The What to Expect When You're Expecting actress started to think more about living healthily following the death of her father 58-year-old father Emilio Diaz from pneumonia in 2008 – but she is keen to ensure the book – which will feature advice from celebrity pals Drew Barrymore, Jennifer Lopez and Paltrow – is not perceived as a diet guide.

The insider explained to E! Online: "Everything changed for Cameron after her father died. She realised what is important and started to think more and more about her health.

"This book isn't about her. And it's not a diet of any kind. Of course, it's her own journey that has helped her realise what's important, but she wants the book to appeal to everyone, and not just be about her own food choices."

As well as writing a book – which is yet to have a working title – Cameron is also planning to visit schools across the US to find out what teenagers enjoying eating and ensure they are making healthy food choices.

The source added: "She wants to use her celebrity to make a difference. She knows she is a role model to girls and she really wants to use that position to do good.

"Cameron is going to be visiting high schools around the country to talk to teenagers about their food choices and what is important to them.

"She wants them to know that being thin should not be their priority, it's about getting the right vitamins and knowing what foods will give them energy and keep them strong. She wants to get their feedback, learn about how they decide what to eat now, and teach them to make more informed choices."