New mum, Kate Middleton, The Duchess of Cambridge enlists her sister to help her get back her athletic body

It’s just seven weeks since Kate Middleton, Duchess of Cambridge, gave birth to Princess Charlotte. And it was clear from photos of Kate larking around with Prince George at last week’s Gloucestershire Festival of Polo that she’s already lost most of her pregnancy weight.

Now can reveal the 33-year old is keen to regain her toned and athletic physique and has hired her sister Pippa Middleton, 31, to be her personal trainer. A source says: ‘Kate wants to get fitter and have a few muscles. She’s very envious of her sister’s body.

‘When the Middletons were holidaying in Mustique in February, Kate was in awe of her sister’s figure after she saw her in her bikini. She made a pledge to herself that she’d start working out as soon as possible after Princess Charlotte was born.’

‘Pippa’s Boot Camp’ is expected to start shortly after Charlotte’s christening on 5 July. Our source adds: ‘Kate has a gym at her Norfolk home Anmer Hall and there’s a swimming pool, too. Pippa’s mapped out a cross-country route for Kate around the grounds. She plans to increase her calorie count by 500 a day so Kate doesn’t burn off more than she gains on her fitness regime. Pippa’s also busy drawing up a high-energy diet that’ll increase Kate’s carbs and protein intake.’

Kate’s always been into sports, proving many times she isn’t afraid of working up a sweat.  Having taken part in competitive rowing and hockey at school, she’s said to be a keen yoga and Pilates enthusiast, too. She’s also a fan of walking, running, swimming and skiing.

Three months after the birth of George in 2013, Kate sported an incredibly trim figure at the SportsAid Athlete Workshop held at London’s Olympic Park. Playing volleyball, she showed off a flat tum and toned thighs while giving the other athletes taking part a run for their money. At the time, Toby French, a volleyball player from Chelmsford revealed: ‘She said she’s played a little before. You can tell she’s sporty.’

We’re sure she’ll be back to her athletic best soon with Pippa’s help.

Kate Middleton is back in her skinny jeans already!

Sofia Zagzoule