09/04/2012 AT 9:15 AM ET
The new season will also tackle the problem of childhood obesity, adding contestants between the ages of 13 and 17 who will compete alongside adult contestants, according to reports. But the teens won’t face elimination on the show and will not be weighed for the broadcast.
Michael’s long-awaited return comes after the fitness guru announced in December 2010 that the show’s 11th season would be her last. At the time, she told fans, “I want to take a year off TV and focus on becoming a mommy and doing more charity work.”