Kim Zolciak Credit:

She gave birth to her fourth child just two weeks ago, but Kim Zolciak is apparently bouncing right back.

The Real Housewives of Atlanta star, 34, welcomed son Kash Kade Biermann Aug. 15 with husband Kroy Biermann. But by Sept. 1, Zolciak's post-baby body was looking seriously svelte.

Her daughter Brielle, 15, Tweeted a gasp-inducing pic of her reality star mom in a long, tight black dress and quipped what everyone else was thinking.

"Seriously . . . who looks like this after 2 weeks of having a baby?"

No word yet on how Zolciak -- who's admitted to hating exercise on Real Housewives -- is dropping the pounds. Kash Kade joins big brother KJ Biermann, 15 months, plus Brielle and Ariana, 9, the Bravo star's daughters from a previous relationship.

Zolciak and Atlanta Falcons player Kroy, 26, wed in Nov. 11, 2011 in a wedding taped for their Bravo spinoff Don't Be Tardy for the Wedding.