Megacorp gave us a lower monthly premium if we had an annual physical exam. No metrics were turned in to Megacorp by doc. I think they just assumed that if you had an issue, seeing your doc would at least give him/her the opportunity to get on your case to improve your situation.
I think it's great to have corporate culture support positive lifestyle changes, but there would be a dangerous slippery slope if performance metrics were reported and acted on in any meaningful way. If penalties become too severe, our courts will become burdened with cases involving ideal weight formulas, safe levels of alcohol consumption, tobacco use (is an occassional cigar OK?), and all that.
If you're going to have significant penalities for non-compliance, determining which behavioral metrics to measure, how to measure them, the absolute values that trigger penalities, length of warning periods, etc., etc., will be a real picnic to figure out. Especially, if any metric has a disparate impact on one sex or a particular ethnic group.