Employers want healthier employees, but at what cost?

It;s comforting to hear that some employers reward employees for good health and solid activities that promote a healthy lifestyle -- but have you ever heard of an employer who punishes employees for bad and unhealthy habits?

The private lives of employees and the quality of work they perform at employers should be kept strictly separate -- right?

Do you agree that private companies should be able to somehow chastise employees for unhealthy habits like being grossly overweight or for smoking?