The new mother has chosen to stop breastfeeding her son.
"It's hard," the 26-year-old Cavallari explained to Hollywood Life Tuesday. "It was the hardest part of the whole thing and no one tells you that. I was a slave to pumping."
Instead of feeding her baby boy breast milk, she has been giving him "a goat milk concoction that [fiance] Jay [Cutler] found."
The slim blonde originally revealed to Us Weekly that she credited breastfeeding for her rapid weight loss after her pregnancy.
"I started working out when he was four weeks old," she said at the time. "Breastfeeding honestly burns 500 calories a day, so that's been very helpful. And I'm a healthy eater in general, so I've just maintained a healthy lifestyle."
Though her fiancé is a big NFL star, she doesn’t want her son to follow in his father’s footsteps.
"I will try to steer Cam in a different direction, maybe a sport that isn't so aggressive," she told DNAinfo.com. "Maybe baseball -- something where he doesn't have to get hit."
But she also made sure to add, "At the end of the day, I think if he wants to play football, I don't know if I'm gonna have too much control over it. How can your dad be a football player and you tell them that they can't do it?"