Designer Michael Costello dishes on dressing ‘tiny’ Beyoncé for the Grammys

Who would have guessed that Beyoncé’s enviable, “bootylicious” curves could squeeze into a size two?

Blue Ivy’s mom looked slimmer than ever while performing “Drunk in Love” at this year’s Grammy Awards on Sunday night, flaunting her lean physique in a revealing, corseted body suit and a black thong.

Later on in the evening, the singer poured herself into custom creation by Michael Costello, which also showcased her super trim figure.

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Now, fashion designer Michael is revealing that the shapely star is actually a petite size two or four.

"We didn't have any of her sizes or measurements," he said in an interview. "The dress was just made to fit a sample mannequin. It's smaller than a size four. She is tiny! That dress is at least a two or four. She looks amazing. I just love the way it all came together. Ty [Beyoncé’s stylist] knew it was going to fit."

MORE: Beyoncé's best Grammys looks

Beyoncé, 32, who completed a 22-day vegan diet challenge with husband Jay-Z last month, revealed that she lost 65 lbs since giving birth to her daughter Blue two years ago.

“I was 195 lbs when I gave birth,” she said in her Self-Titled documentary. “I worked crazily to get my body back. I wanted to show that you can have a child and you can work hard and you can get your body back.”

The singer’s small dress size may come as no surprise to those who have seen celebrities in person. Bombshell Marilyn Monroe, who was also known for her curvaceous figure, is estimated to have been a svelte size six.

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