I don't either. And I also have an issue with Medicare/Medicaid paying the medical costs of people with health problems from smoking or overeating. However, I also realize that just letting people die can be cruel.
The other problem is, what type of law would you pass to "discourage" people from getting fat? Have mandatory weigh ins each month? That's gonna screw up those with lots of muscle mass. I could list the numerous problems here, but that would take too long.
The solution lies in the private sector. Health insurers should provide incentives for those who live a healthy lifestyle. Some insurers already do this. Businesses should encourage employees to take exercise breaks. Maybe give them one day off each month for "exercise" day.
What can the government do? Provide tax breaks to those insurers that provide incentives for healthy living and businesses that provide employees with time off for exercise. Business and individuals should be given tax deductions for the purchase of exercise equipment for the workplace and the home. Granted, buying exercise equipment and using exercise equipment are two different things, but it would be a start.
Government should facilitate solutions that come from the private sector, not regulate the heck out of people's lives.