Beyonce on November 20, 2011 in New York City and performing on May 25, 2012 in Atlantic City, New Jersey. Credit: Rob Kim/FilmMagic; Kevin Mazur/

Beyonce's bootylicious body is back!

"Y'all have no idea how hard I worked. I had to lose 60 pounds!" the svelte singer shouted from the stage of her May 26 concert at Atlantic City's Revel Resort. "They had me on that treadmill -- I ate lettuce!"

The 5-foot-7 singer, 30, prepped for her first gig since the January 7 birth of daughter Blue Ivy with trainer Marco Borges, who led five-days-a-week cardio and body-sculpting sessions.

The "Countdown" singer also stuck to a whole-foods diet, including "vegetables, protein, nothing packaged," Borges tells the new issue of Us Weekly (out Friday).

So how is the star celebrating? As she told the crowd, "I'm gonna get chocolate-wasted!"