There are a number of issues with this. 1) It functions like a regressive tax, a tax on poverty. Obesity strongly correlates with economic level. 2) The burden of such of policy would be disproportionally felt by minority communities. 3) It disincentives people from seeing health care providers. Gain 10lbs over the last year? Maybe you skip this year's Dr appointment so you don't have to weigh in. 4) It gives your employer access to your health information (assuming you're talking about employee health insurance). There are a ton of reasons why your employer should not have your health info which I don't think I need to detail, but one additional problem is that it forces all employers to maintain HIPPA complaint record keeping, which is no small task. 5) It seems unlikely to actually work to me. I'm no expert in obesity, but anecdotally the few obese people I've chatted with about their weight badly wanted to lose weight. Their issue was not solely motivation. My first thought was the people making claims are typically older and much so once you get close to retirement age. If we started trying to skew premiums towards those higher risk groups you would create an even bigger problem with older people being able to afford healthcare. People should just think of higher premiums at a younger age as prepayment for their later years. Skewing those payments towards later years would require people to acknowledge that and plan for it...I don't have confidence in people doing that. Additionally, everything you stated I tend to agree with. I think all you would do is create a bigger need for government assistance with healthcare and I don't think that is benefitting the people needing it or anyone else.