Skinny jeans six weeks after delivering daughter Charlotte? When you're Princess Kate, yes.
In this week's cover story, PEOPLE exclusively reveals the secret to her fit form: a top London trainer who worked with the royal mom, 33, throughout her pregnancy.
The trainer, who is popular with an elite clientele of A-listers, royals and executives, "was brought on board while she was pregnant and is super-discreet," a source tells PEOPLE.
"It's a lot of money, but you get a lot for the price."
Included in the package is a tailored fitness routine and regular monitoring.
"The trainer checks in remotely with Kate by phone every day as well as seeing her in person once a week," says the source.
As for diet, Kate – who breastfed Prince George and is likely doing the same with Charlotte – is a clean eater who has always gone heavy on organic fruits, veggies and lean meats.
The trainer embraces a similar philosophy – with a high-end twist.
"The food is very elegant and actually feels like food you would eat at a restaurant," says the source.
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"The whole program is very sensible – it's not fad-based and is really focused on your overall health and well-being."
For much more on Princess Kate – and her sweet bond with Prince George – pick up this week's issue of PEOPLE, on newsstands Friday
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