Gwyneth Paltrow had a ''long butt'' and ''outer thigh problems'' after giving birth.

The 'Iron Man 3' actress has credited Tracy Anderson's diet and exercise programme the Tracy Anderson Method for her impressive figure, but the fitness expert reveals Gwyneth was struggling to get the body she wanted when she was unable to shift the pounds after giving birth to her son Moses in 2006.

Tracy was introduced to the Hollywood star through one of her clients and offered to get her into shape after noticing she had ''significant problem areas''.

Tracy revealed: ''I agreed to meet with Gwyneth, and she said, 'I've got this movie coming up where I have to be a superhero.' It was the very first 'Iron Man'. She said, 'I know you have a son - I just had Moses - and I can't get this weight off. I've never had a problem like this in my life.' She had 35 extra pounds on her. Her butt was long and she had outer thigh problems. Gwyneth is lucky because she's really tall, so she can hide it really well in clothes, but she had significant problem areas.''

Although Tracy agreed to train Gwyneth and help her get the figure she wanted, the fitness expert insists the actress deserves all the credit for her enviable body.

She added: ''I thought I could really help. So, I agreed, and she did everything that I asked. Now, seven years later, she looks younger every year - she's totally transformed. And she really does the work.''

The 40-year-old star - who also has daughter Apple, nine, with husband Chris Martin - was so enamoured with Tracy's methods they became business partners and close friends.

Tracy explained to ''She said, 'Every woman has to have this. It's not fair. I've tried everything and nothing works like this. You're a real gift.' It wasn't a business decision for her at all.''

Gwyneth is just one of the A-list names who has relied on Tracy's diet and exercise plan to maintain her physique. The fitness guru's clients also include Madonna, Kate Hudson and Shakira.