U.S. first lady Michelle Obama (in red) reacts as she is welcomed by traditional dancers after arriving at the Sir Seretse Khama International Airport in Gaborone June 24, 2011.

U.S. first lady Michelle Obama and her mother Marian Robinson (L) watch as traditional dancers perform during their arrival at Gaborone June 24, 2011.

Michelle Obama dances with children as she visits the Emthonjeni Community Center in Zandspruit Township, Johannesburg, South Africa June 21, 2011. U.S. First Lady Michelle Obama paid a visit to former South African President Nelson Mandela on Tuesday, kicking off her own symbolic trip to Africa by meeting one of the continent's most revered leaders.

Exercise to fight cellulite. First Lady Michelle Obama dances during a surprise visit to Alice Deal Middle School for a Let's Move fitness event in Washington in this file photo.

U.S. first lady Michelle Obama, seen with a hula hoop here, needs to be more aware of her eating decisions.

U.S. first lady Michelle Obama kicks a ball as she attends a free soccer clinic organised by the U.S. Soccer Foundation in Washington March 5, 2010.

U.S. first lady Michelle Obama dances with children during a visit to the Holy Name High School in Mumbai, India, November 7, 2010.

U.S. first lady Michelle Obama performs a drill before playing flag football with children, former NFL players and coaches, during her "Let's Move" campaign to fight childhood obesity in New Orleans, September 8, 2010.