Sounds like a pretty good solution to me. Companies have a financial interest in having healthy productive employees, so it only makes good sense to hire people who are likely to remain healthy and productive in the long term and those who don't like it can either find work somewhere else or change their lifestyles.
I get your point, but there are some people who have valid cause for their size. Pituitary tumor, for example. Without the job and the insurance, correction becomes financially impossible. I know a lady like this who is a nurse. In fact, nurses are sometimes more heavy than non-health professionals. That's kinda scary. Has to be partly due to the high stress. IMHO.
These are the same people who "celebrate" the gay lifestyle, which, according to health statistics is a very unhealthy way to live.