That's hardly the same thing. Drug use has implications beyond the individual.
Nearly all actions have some implications beyond the individual. I'm not sure why someone poisoning themselves to death on an arbitrarily designated chemical compound is considerably worse than any other method they want to use to destroy themselves.
Obesity sometimes does too but until it becomes a major cost to the public no one will want to regulate it.
Major cost? At least
http://www.surgeongeneral.gov/news/testimony/obesity07162003.htm'" target="_blank">$117 billion per year in 2000 according to Surgeon General Richard H. Carmona. Much, much more when type 2 diabetes is considered.
The National Institute on Drug Abuse puts their estimate at the cost of
all illegal drugs combined at
http://www.nida.nih.gov/Infofacts/costs.html'" target="_blank">$97.7 billion. Dealing with alcohol (a legal drug) alone, the costs are around $148 billion.
Obesity and the conditions it causes currently costs our nation more than all illicit drugs do combined.
Nor is there an obvious target to regulate since a person could make himself obese by eating corn flakes.
Some foods are more fattening than others. Foods with more greases, refined sugars and such are worse for you, right?
I have no more desire to pay for some coke-fiend's health care than you do. Less, probably, as I would prefer to let someone who makes the willful decision to destroy themselves in such a fashion achieve their goal or at least depend on their loved ones and charities instead of the communal pocketbook. But if you're going to say
"Your actions affect me because if you get hurt and can't pay for yourself, I have to pay for you. Therefore, upon pain of imprisonment, everyone is forbidden to _____________," then you need to consider that everyone risks their life and health (and thus, our money) every time they drive into work, walk in the park, have sex, move furniture, ride a bike, eat at a restaurant, and anything else they might do.
The solution as I see it is not to work legislatively to dictate how people should live their lives to be less of a burden (or risk of a burden) on society, but to change the rules in society to shift the burden of responsibility for caring for ourselves to ... well ... ourselves.
But then you agree that controlling immigration is counter to the idea of freedom and we need open borders, right?
No. When exactly did I mention immigration?
Oh, right. Now I get it. Because I'm not rabidly anti-drug, I have to be a dyed-in-the-wool capital "L" Libertarian lackey with complete adherance to the party line. Is that about what you're trying to imply?