I assure you, we already are forced to pay the obesity bills.  With the system right now, we wait until people need amputations and cardiac caths and a lot of super expensive interventions before we will cover their medicine and foot care.  It's pennywise, pound foolish.  With nationalized health care there will be more of an incentive to practice preventative medicine.  And maybe then we can punish parents who let their children get fat.