January 05, 2014 - 12:37 GMT hellomagazine.com The young royal's personal trainer has revealed the secret behind Princess Beatrice's dramatic style and fitness transformation over the past five years Princess Beatrice's personal trainer has revealed the secret behind the young royal's dramatic fitness transformation over the past five years. Since the age of 18, Beatrice has gone from being a body-conscious teenager to a fit and fashion-forward princess, often praised for her chic style and healthy figure. Personal trainer Nadya Fairweather, who works with the royal once a week when she is in London, praised Beatrice's determination and balanced approach to food for getting her into perfect shape. The duo have been training together since Beatrice was 18, when she first sought Nadya's help after pictures emerged of her in a bikini while on holiday with her long-term boyfriend Dave Clark. The then-teenager was criticised for her curvaceous figure and sought Nadya's help. "It was very upsetting," Nadya told The Express. "She was young and I don't know any 18-year-old who has not had a bad photograph taken of them, especially in swimwear, so that is when our relationship started. "She just thought, 'Right, I need to get myself in shape because I will never get out of the media,' so we started working together. "Beatrice is in great shape. She eats really healthily but she eats, which is massive in a celebrity world full of people starving themselves and doing crazy fad diets. Beatrice has beautiful curves and she embraces that. "She does plenty of training on her own between our sessions which makes it easier for me to keep challenging her with new equipment and different styles of training." The 25-year-old, who became the first royal to complete the London Marathon in 2010, eagerly prepared for the 26-mile race shortly after starting Nadya's outdoor training work-outs in the city's parks. "She decided she wanted to run the marathon so I got her ready for that," said Nadya. "That was an amazing personal challenge. She climbed Mont Blanc about a year ago too, she really loved it. She found it so challenging but amazing. She said it was brilliant and she felt fit, which was really good." The personal trainer added that Beatrice "works hard in every session and trains in all weathers without a single complaint."