Everyone knows about Beyoncé singing, or, not singing, "The Star-Spangled Banner" at President Obama's second-inauguration event, but what about the singer who actually did sing-Kelly Clarkson?

Her arrangement of "My Country Tis of Thee" that many consider the strongest performance of the event prompted a US Marine Corp Band representative to tell Reality TV Magazine, "Clarkson belted out her song without the assistance of a backing track."

Another shot at Beyoncé-those words have to hurt. Maybe, the reason why she left the ceremony early was to avoid the backlash?

In the middle of Clarkson's song, the camera caught President Obama saying "wow."

But, where does the real credit for her stunning rendition lie?

According to Reality TV Magazine, it is all about stuffed mushrooms from Washington, D.C.'s Buca Di Beppo.

TMZ took it even further, reporting that, in addition to the stuffed mushrooms, the singer, along with her friends, ate spaghetti, chicken parmesan, lasagna and other dishes.

She ended the evening with a ginormous brownie sundae and a bill of $230.

The next day, she left the crowd and President Obama breathless. Not just by her singing, but by her dress, which she wore the night of the inauguration and the night before at the resultant.

The issue: she couldn't fit the dress into her car's backseat door.

"My dress barely fit in the car for tonight's festivities. I feel like Cinderella! Thank you Oscar De La Renta!," she said, while leaving the restaurant, according to Reality TV Magazine.

Could it be that after all this time Kelly Clarkson's secret has finally been revealed?

Could it be that the secret is, filling up on the carbohydrates the night before?

Take a listen.

Does the theory make sense?