Natalie Portman Writes Foreword for Ballet Book by Mary Helen Bowers [PHOTOS]

The Hollywood actress Natalie Portman has written a tribute for her ballet trainer Mary Helen Bowers' new book.

In Bowers' new fitness book "Ballet Beautiful," Portman, 31, credited her trainer with helping her learn advanced ballet moves for the 2010 film "Black Swan," for which Portman won an Oscar last year.

"My posture looked like I'd swallowed a broom... I had the same body since (I was) 14," Portman wrote.

"With Mary Helen, it's completely transformed. I gained length, strength and tone. Arms and legs changed shape. In awe of dancers' bodies - definition in their arms, strong legs and beautiful line extending from fingertips to toes... (plus her) healthy diet in conjunction with the exercises achieved our fitness goals."

Portman had lost 20 pounds and trained eight hours a day for her role as a troubled prima ballerina in the 2010 film.

Created by the professional ballerina and the "Black Swan" trainer, "Ballet Beautiful" provides "techniques to build and maintain the beauty, strength and grace of a ballerina".