A Middleton family source told UsWeekly.com, "She's hardly done anything to lose the weight …She looks incredible. Kate's still breastfeeding and the small weight she gained while pregnant has just melted off. She's not dieting. After giving birth, she did continue with her yoga."
The royal family is currently staying in Anglesey until they move into the newly renovated 20-room Apartment 1A at Kensington Palace in September.
The insider said, "They've been in Anglesey for almost a couple of weeks and their lives are much more active there -- lots of walking, lots of time in the outdoors. And the weather has been great. I'm sure they have been making the most of it."
Earlier this month, Prince William and Kate posed with their little Prince George for an informal family portrait.
[Photo: Getty Images]