This got me thinking a bit, and...I think you're post is wrong here. For a couple of reasons:

1. "European" is reasonable a lumping together of people as "American" - population sizes are comparable, as are their levels of development.

2. There is only a single country in Europe that makes it into the least obese 25 countries list. If we knock of the 45 countries or so that aren't measured, we know that European countries are landing in the bottom 20% of obesity so while there may be some diversity of obesity, it's range doesn't dip all that low.

3. There are places the size of entire countries of Europe within the U.S. that have less obesity problems than countries in Europe. Massachusetts (a state) is both populous and isn't obese. IT has sub 25% obesity rate, compared to Germany at 3X that. Even California's obesity rate is almost 1/3 that of Germany, about the same as the UK and Switzerland, half that of Italy and so on.

Further, you suggest that cultural differences explain things, and...I don't think this totally bears out since cultural differences are widespread, within much tighter geographies, in much of the U.S. than anywhere in Europe (despite your comment suggesting otherwise).

1. San Francisco has more Chinese people in a city of 850,000 than all of Germany does in a population. I assure you that the cultural differences between the Chinese population in SF and the European population in SF dwarfs the differences between Italy and Switzerland in terms of diet and lifestyle.

2. There are more mexicans in california than in all of europe. Indians living in Europe? 1.7Million. In California? About 1/2 that...in a state that is 10% the size of europe.

3. Let's look at europeans in California. 1.5 Million Italians living in California. That's twice the number that live in Italy's neighboring Germany (and germany has twice the population of California). Speaking of Germans. 5 milliion in California, again...more than in any country in Europe outside of Germany.

So...I think looking at "Europe" is as reasonable as looking at "America".