Beyonce Knowles attends the "Schiaparelli And Prada: Impossible Conversations" Costume Institute Gala at the Metropolitan Museum of Art on May 7, 2012 in New York City. (Source: Larry Busacca/Getty Images North America)

Beyonce's back! The new mom performed for the first time since giving birth to Blue Ivy this weekend in Atlantic City. Of course, the she blew audiences away with her powerful voice, impressive dance moves, and her unbelievably fit post-baby body.

The singer performed in front of 5,500 fans, including Michelle Obama and daughters Sasha and Malia, at Revel Resorts Saturday night. She sang a whopping two dozen songs, opening with "End of Time," then peppering in hits like "Crazy in Love" and "1+1." The songstress also joked about how hard she had to work to look good her multiple glitzy, pantsless costumes. "I had to lose 60 pounds. They had me on the treadmill, eating lettuce," she told the crowd (via AP).

Knowles performed Friday and Saturday nights at the same casino, and has also scheduled shows for Sunday and Monday. Leave it to this gal to jump back into four back-to-back shows after a five-month break! She won't be needing the treadmill after this exhausting holiday weekend, that's for sure.

Bey also paid tribute to some of her late idols during the evening. She sang a verse of Whitney Houston's "I Will Always Love You" and also gave a shout-out to Donna Summer before singing "Naughty Girl," which samples the disco legend's hit "Love to Love You Baby."