Gwyneth Paltrow is reportedly planning to write an adult guide for married couples.

According to editors at Heat magazine, the 45-year-old actress and lifestyle guru, who is engaged to Brad Falchuk, has reportedly told friends that she wants to write an adult guide to carnal pleasure for married couples, and is alleged to be angling for a $513,000 (£400,000) advance for her efforts.

“She’s already started writing it,” a source close to the star told the British magazine. “So far the chapters are dedicated to the Earth’s elements and will show how to use fire, air, water to have incredible physical relations while married.

“There is also a section on using recycled plastic products and food to play to tease your man. It demonstrates the art of sucking on low-calorie fruits and vegetables!”

One person who might not be so keen on the book is her ex-husband Chris Martin, who is the father of her two children Apple and Moses.

The pair have remained close since they “consciously uncoupled” in 2014, with the divorce finalised in 2016.

However, the Coldplay star is reportedly worried Gwyneth’s fans will think she is sharing experiences from their 11-year union, as she and Brad have yet to marry.

“He finds it a bit embarrassing and has asked her to wait at least until she is actually remarried before she publishes,” continued the source. “Brad has given his full approval, but he said there better not be anything in that book she learned from Chris.”

Goop founder Gwyneth isn’t reportedly making any promises.

The news comes after her lifestyle website recently published a 300 page e-book titled, The S*x Issue: Everything You've Always Wanted to Know about Sexuality, Seduction, and Desire.

It contains expert opinions and anecdotes on topics ranging from the art of orgasmic meditation to the benefits of partaking in a sacred snake ceremony.