Neither of the bills that have passed the house have a personal mandate. If you want to do without health insurance, good luck.
I personally am opposed to personal mandates, and always have been, so this is an issue I'm paying attention to. The mandate does seem to be popular in the senate, but we'll have to see what is in the final bill.
However, there is no doubt that being fat (not overweight according to some utterly worthless BMI scale, but FAT according to body fat percentage or waist-to-hips ratios) carries higher health risks and greater health care costs. That has been confirmed by every study that has been done.
Moreover, the fatter a person is, the greater the health care costs and higher the health care risks become.
It's currently estimated that America's expanding girth is responsible for an additional ~160 billion or so dollars in health care costs. While that's not much compared to what we spend, it's growing... As the fat people grow older, their dedicated share of health care issues will rise.
If, in 10 years, the 30% of America that are fat cost America an extra 500 billion dollars in health costs... we will have to decide whether we want to increase THEIR health care costs by 50% to pay for that increase or whether we want to increase our health costs (and theirs) by 18%... Since it's THEIR lifestyle choice that costs extra, I favor asking them to pay up.
*shrug*