She came back to town Wednesday evening to promote her anti-childhood obesity campaign "Let's Move".
After arriving in her hometown, the First Lady dined in the private dining room at River North restaurant RPM Italian with a female friend, according to restaurant spokesperson Kathleen Henson. She surprised diners who erupted into applause as she walked in the restaurant's front door.
Obama will be joined by famous athletes including Olympic gymnast Gabby Douglas and tennis superstar Serena Williams to announce a new initiative to promote healthy recipes on several media companies' websites at McCormick Place Thursday.
She talked about her work on the 3-year-old "Let's Move" campaign on "Good Morning America".
"When we started, there were a lot of people in this country who would have never thought that childhood obesity was a health crisis," she said. "But now, we're starting to see rates of obesity coming down like never before."
On Wednesday Obama traveled to Mississippi, a state which has seen a drop in child obesity rates thanks in part to new health standards for school lunches.
"You schools did hard work, she said. "They replaced their fryers with steamers. Hallelujah!"
She was joined by celebrity chef Rachael Ray.
"I think we're finally getting that momentum going as a nation that we're going to see this through. We are actually going to see some change happen," Ray said.
It will be Obama's second appearance in Chicago in February.
On February 9 she attended the funeral of slain teenager Hadiya Pendleton.
"She was standing out in a park with her friends in a neighborhood blocks away from where my kids grew up, where our house is, and she was caught in the line of fire," Obama told GMA anchor Robin Roberts. "And I just don't want to keep disappointing our kids in this country. I want them to know that we put them first."