Health care should be reserved for those that care for their own health.  I get where you're coming from here but how would something like this be implemented? You'd have to do a lot of investigating into a person's life to determine this, beyond just weighing them. There are a lot of thin people who eat like shit, who smoke, who are weekend alcoholics, who never exercise, or who otherwise put no effort into their bodies and their health. There's also the whole healthcare as a human right thing...it'd be hard to convince an entire society and its government that healthcare is a privilege that only the fit can access.