(Cover) - EN Star Style - Tracy Anderson says Jennifer Lopez has a "beautiful shape".

The personal trainer has worked with a host of stars including Gwyneth Paltrow, Madonna and Courteney Cox Arquette.

Jennifer enlisted the help of the fitness expert ahead of her debut on the judging panel of American Idol earlier this year.

Tracy says she targeted Jennifer's butt and legs when training the stunning star.

"We worked on everything but especially on her bottom and legs. She has a beautiful shape so we wanted to keep that, but we also got her bottom lifted back up to its pre-pregnancy position and got her legs looking long and feminine with better skin tone," she explained in an interview with Closer magazine.

Tracy has revealed her workout plan with Jennifer. The fitness guru says Jennifer's enviable body is the result of exercise repetition.

"We do 8-10 different leg movements I've designed for her with about 40 repetitions on each, then we swap to the abs, then arms with or without 3lb weights. Then we do dance aerobics for 40 minutes," she said.

Tracy didn't give Jennifer any diet advice. The A-list trainer says the beauty didn't need help, as she is already a very conscientious eater.

"No, she wasn't very overweight anyway and is a very healthy eater. She doesn't diet as she works out so much. I only get involved in people's diet if they are very unhealthy," she added. (C) Cover Media