Thanks to a "surprise treat" from little sister Pippa Middleton, second-time mom Duchess Kate has fresh green juices delivered regularly Credit: Karwai Tang/WireImage

As the Duchess of Cambridge Kate Middleton cares for her two under 2 — 22-month-old Prince George and 1-month-old Princess Charlotte — sister Pippa Middleton is looking after her.

"Pippa arranged to have fresh juices delivered to Kate every three days," says a family source. "It was a surprise treat. Kate used to blend her own juices and this is much easier." (Last year the British press dubbed her "Smoothie Queen" for her purported love of the NutriBullet mini-mixer.)

The new mum, 33, drinks the elixirs in her 10-bedroom Anmer Hall estate in Norfolk, but is not dieting, clarifies the confidant. "She just enjoys green juice in the morning. It's Kate's go-to for an extra boost."

Husband William, 32, is also a convert thanks to his 31-year-old sister-in-law, who is studying to be a nutritionist with an eye toward writing a book on healthy eating, according to the source. "Pippa was the one who got them into juicing. They all love it!"

As part of her health kick, Kate has been frequenting Back to the Garden, an organic farm shop near the tiny Norfolk village of Anmer (population 63). "She's buying fresh local produce," says a source. "All organic." And the princess is just plain folks amongst the locals, adds the source. "People give her space. No one is rushing over to ask for selfies."

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