Excerpt: When Blue Cross and Blue Shield of North Carolina scrutinized medical costs and claims data for its obese members, it discovered that their care cost at least 30 percent more than normal-weight members. That's when the Chapel Hill-based plan decided to wade into the high-cost, high-stakes world of obesity treatment, rolling out a benefits package that observers describe as one of the most comprehensive available. Now comes the tricky part: getting employers to foot the bill.