Actress Gwyneth Paltrow does 12 hours' worth of exercises each week just for a perfect derriere.

The 43-year-old, who has her own lifestyle site GOOP, undertakes a gruelling two-hour exercise regime six days a week, and it is devised by her personal trainer Tracy Anderson.

Paltrow claims the regime which she intensifies by adding extra weights to her ankles for extra definition, has left her with a behind that is comparable to a "22-year-old stripper".

"With my method I go after restructuring your muscles so that they are designed to not only be strong but combat problem areas... It's really hard. But do it like she (Tracy) says to do it and I swear that in ten days you will see your butt change shape.

"I do it with one pound ankle weights and then I do her Dance Aerobics DVD. Some days I hate it, some days I love it, but above all, I stick with it,` she said.

"With this leg and butt series it is very important to do all of the reps and moves on one side then go to the other leg. I lay out my sequences to accomplish visible results.

"I exhaust the large muscle groups and then call on the accessory muscles to become active and alert. This works wonders with skin tone and structure,` added Paltrow.