Credit: Barcroft/Fame Pictures

Middleton's a bit littler.

As previously reported on Us Weekly, Kate Middleton shopped for honeymoon gear in London's Kings Road neighborhood on Tuesday -- checking out mid-range items like a $105 Tropical Bird Print Dress at the store Warehouse. (See more photos from Kate's shopping trip.)

New pics of the 29-year-old Princess-to-be's day out reveal a slimmed-down look for Prince William's love, set to wed on April 29. Middleton smiled her famous grin on the windy day, wearing a blue wrap dress that showed off her increasingly petite frame.

An athlete all her life, Middleton has been getting in even better shape for her nuptials with regular workouts at London's posh Harbour Club, which costs $3,500 to join.

But don't worry about Middleton overdoing it, a palace aide tells Us. "Kate's not on a diet," the source says. "She's not been trying to lose weight. She's a healthy girl who loves her food and doesn't count the calories. Because she's always been rather sporty, her metabolism is naturally quite high." (See more photos of Kate Middleton's baby bump debut via PopSugar)

Adds the insider: "Staying in shape is important [to Kate], and she does exercise, but this isn't to get smaller."

For more on the Royal Wedding, including rare photos, interviews with family and friends, details on Kate's new life as a princess and a tour of their lavish homes, order a copy of Us Weekly's Will & Kate: The Royal Wedding now.