Been all around Europe. Europeans are smaller but only because they're not fat. It really shows what Americans are. In Europe, people just don't eat as much. Part is historical/cultural. Part is $. In America, people just eat, and eat. 3 meals or more a day. Over there, two small meals a day is common.
Smoking is a different issue entirely. You're more likely to smoke if you're bored and don't think much about the distant future. A lot of European countries are so screwed up with their borderline socialist economic systems that the average citizen doesn't have much of a chance of changing socioeconomic brackets. = boredom. = smoking.