Princess Beatrice Marathon training

Mar 17, 2010, 13:25 GMT

Britain's Princess Beatrice is the fittest member of her family.

The royal - who is fifth in line to the throne - believes training for the London marathon next month has helped boost her levels far beyond that of her parents Prince Andrew and the Duchess of York, though she thinks her younger sister could soon catch her up.

She said: "If you mean my immediate family I'd say I was the fittest. But my sister, Princess Eugenie, is a keen runner, so maybe she has a marathon in her future.

"Out of my extended family, I'd have to give it to William and Harry though."

Beatrice, 21, also told how she was initially reluctant to commit to the 26-mile run, and claimed her course at London's Goldsmiths College was too taxing for her to take the time to train.

She told Britain's Hello magazine: "It took a lot to get me involved I tried to come up excuses about all my lectures and work at University, but it has turned out to be the most exciting time of my life. I had never taken fitness seriously before.

"I feel different - mentally and physically fitter. I never think about dieting and I don't even know what size I am, I just go by my clothes, if they feel tight or loose."