Different European countries have different circuimstances, just like their counterparts, american states. But if we're talking about all of Europe and US, then yes, this is the main reason.
Where are you getting this data from? Nicotine is an appetite suppressant but so is caffeine. I find it hard to believe that smoking alone is the reason for the difference.
Source ?
Lol, crazy theories require real proof. Netherlands: 10% obesity rate, 12% smoking rate.