Casey Rodgers/Invision for Ubisoft/AP
01/19/2014 at 04:00 PM EST
Prepping for baby No. 2 is clearly no sweat for Kristin Cavallari
– unless you count her workout sessions.
The reality star-turned-designer, 27, who's expecting her second child
with husband Jay Cutler – took to Instagram on Saturday to show off more than her fit form – check out that baby bump!
"Gym selfie," she writes
. "Baby bump getting big!" (Check out her "healthie
Since debuting her baby belly
in November, she's kept mum on whether son Camden, 17 months, will be joined by a little brother or sister.
"It's harder because I'm tired, and then I still have to be a mom to Camden," she told PEOPLE
of her pregnancy. "But it is easier in the sense that I know what to expect."