It is illegal for kids to smoke and drink in the US because of laws passed by legislators, it is not like it was in the Constitution (although Prohibition was added for a while which is interesting to add to this discussion). Again, what's the difference? Do you think that obesity is less of a problem than people dying of alcohol related diseases? The fact is, all of those things are bad for people. Yet, you are saying you have no issue with the laws about tobacco and liquor yet you do about food that is bad for you. That is your personal line, but they are absolutely comparable. Some people have a different line which is that obesity is such an issue that it is time to legislate solutions. Do I agree? Nope, but I don't see it as any different than Prohibition and the tobacco advertising rules.