Kate Middleton says baby George has gotten fatter while on royal tour Credit: Scott Barbour/Getty

Prince George has grown an "extra fat roll" while on the royal tour in New Zealand and Australia, jokes his royal mom Kate Middleton.

The Duchess, joined by Prince William, continued their royal tour on Tuesday, April 22, touching down in the Northern Territory in central Australia, first visiting the National Indigenous Training Academy and then making their way to a tea party at the Uluru-Kata Tjuta Cultural Centre, which tells the story of Ayers Rock and the Aboriginal people who consider the site sacred.

Middleton, who donned a Hobbs gray and white dress she recycled with espadrille wedges, joked with students about the future King of England's baby fat and his tendency to get "grumpy on the long flights."

When asked by 17-year-old student Shannon Hunt if the couple missed Prince George, who stayed back with nanny Maria Teresa Turrion Borrallo, the 32-year-old mom joked her 8-month-old baby boy is getting bigger by the minute. 

"We asked if they missed him," Hunt tells Us Weekly, "Kate said, 'He's been changing so much while we've been away.'" Adding, the royal even laughed, he grew an extra fat roll!

"She also said he can get a bit grumpy on the long flights," the 17-year-old added.

The Duke and Duchess then headed to Ayers Rock, the nation's largest natural sandstone. A landmark which Middleton was eager to see, as she told another student: "I've heard all about [the sunset]. It'll be very memorable."

But first, Middleton and Prince William took a photo with the students. Initially asked to take a selfie with the group, the couple obliged to taking a more typical photo with William joking: "Well, If you don't mind having a photograph with us!"