"My man, Gerard, prefers meat over bone. He doesn't like too skinny," she playfully tells Glamour for its February cover story, on sale Jan. 14 (available now digitally). "That takes the pressure off. I already have a lot to worry about."
For the Colombian native, 36, this translates into less time at the gym because, as she puts it, she simply has other priorities.
"This month I'm not exercising because I have an album to finish and I have a baby," she says, referring to son Milan, who turns 1 later this month. "And I like these pastries in front of me."
The singer is also gearing up to resume her coaching duties on The Voice, whose season six premieres Feb. 24.
Taking Christina Aguilera's former seat, she will be the sole female coach, alongside Sexiest Man Alive Adam Levine, Blake Shelton and Usher.
Working with men in the male-dominated music industry is nothing new for the mega-star, though she does admit that being surrounded by so much testosterone took some getting used to.
Nicolas Moore / GLAMOUR
"There are jokes made almost every second of the day," she continues. "I had to develop a tough hide."
Having a sense of humor – not to mention impersonation skills – no doubt helps, as evidenced by this photo of her imitating her adorably fussy baby boy.