Once known as much for her pleasingly-plump frame as she is for her booming vocals, Oscar-winning R&B powerhouse Jennifer Hudson is sitting pretty at a sleek Size 4 — and she plans to keep it that way, much to the chagrin of her baby-crazed fiance.

Jennifer is already the mom to 16-month-old son David Jr. with Harvard-educated wrestling star David Otunga, 30, but the happy couple are at odds over David’s desire to add another child to their brood, a family insider recently snitched to The National Enquirer. Hudson’s dropped 80 pound since signing on as the face of Weight Watchers and is absolutely appalled that David would have the unmitigated gall to want her to get pregnant again after all of the hard work she put into ditching her Size 16 frame.

“David wants David Jr. to have a little brother or sister, and he thinks a two-year age difference would be ideal. But Jennifer has finally got the body she’s dreamed of and knows how much it took to get back and stay in shape after the birth of their son,” The Enquirer insider says. “He still brings it up from time to time and it causes arguments, but Jennifer is determined to enjoy the way she is now for a while before she has to put her life on hold again.”

Those close to the couple believe David may be feeling insecure that Jennifer, 29, is no longer the hefty Chi-Citian she was when the pair first fell in love in 2008.

“Heads turn when she walks into a room. I don’t think David is used to that. Jennifer told David she does want another child, but not now.”