The singer is currently expecting her first child with fiancé Eric Johnson, but is apparently in talks to lose the baby weight using the plan and then become a brand ambassador.
A source told Us Weekly that the 31-year-old, who is engaged to ex-NFL star Eric Johnson, had been planning to sign up to lose a few pounds anyway.
'But then she got pregnant,' said the insider. 'So this was the perfect compromise.'
It is thought that she will have one year to 'lose a significant amount of weight' on the plan, before showing off the results in an ad campaign.