If the employer pays 100% for your Health Care, everything included, than maybe they can set down some rules of healthy living so to speak.
If you are required to pay co-payments the deal is off, period! IMHO!
If an employer wants to offer you that deal, and you take it, then that's what you're worth. Period. Employers are shoppers just like you are. If you have two equivalent 5lb bags of oranges next to each other, and one costs $5 and the other costs $3, which one will you buy?
Free markets work. If you don't like the deal, don't take it. It doesn't matter if you're talking about oranges or jobs, it's all about value.