I believe that culinary customs AND some additives used in industrial food play an important role.
Just check out High Fructose Corn Syrup : this is in very product in the USA and is (almost) never used in Europe.
The problem with HFCS is not HFCS, it's that the US government has subsidized corn production, lowering the price of corn, lowering the price on a sucrose-analog and increasing the total amount of sucrose-analog in the American diet. See Earl Butz [ http://en.wikipedia.org/wiki/Earl_Butz ].
Fascinating charts. Compare: http://upload.wikimedia.org/wikipedia/commons/5/5e/Usda_swee... and http://upload.wikimedia.org/wikipedia/commons/c/c1/USObesity...
I've dealt with vendors from southern France and Western Italy and when they come here they are shocked at portion sizes and how much pop people drink, it's all anyone drinks. Even I see the difference from many years go portions are huge even people are huge, it's hard to find clothing that isn't over-sized and baggy.
Claiming corn syrup is bad meanwhile people drink it morning, noon and night seems to indicate it's equally the fault of a culture that is comfortable with eating so much crap but seeing it as normal then blaming it for their problems.
At work we have a pop machine which up until a few years ago due a provincial law could only dispense glass bottles, all carbonated beverages had to be in a glass container. The glass bottles were about 315ml, then the law changed (because people wanted cans) and the next day the pop machines was stocked with the modern plastic bottle but they were nearly 600ml. The fridge at work was full of half bottles of pop because people couldn't drink their 600ml beverages in one sitting but gradually over the next month or two people adjusted and now drink the entire 600ml in one sitting almost double. HFCS or not who is to blame for that? The person drinking it.
The person drinking it is "to blame" for what, precisely? Being a creature which can adjust to its environment? Why does any blame need assigning? Who benefits from assigning any blame?
French schools serve real food on real plates - a portion of moules marinière or escargot would be completely familiar fare to most french kids. Even lardy Britain is changing school meals from mere fuel to an integral part of a child's education.
American food culture is one of abundance - eating large quantities of the richest foods. The humblest of American meals are based around meat in great quantity. Italians still eat a prima piatti of something cheap and filling before a relatively small secondi piatti of meat or fish, a cultural legacy from harder times when meat of any sort was a treat.
The tide is certainly turning and obesity rates are soaring, but the difference in rates is largely accounted for by cultural difference. The French rightly see it as a crisis that students don't want to sit down for meals anymore. Most of Europe sees food as a vitally important political and social issue.
If everyone around you is behaving in varied ways with respect to food, you may be more likely to make decisions based on price, convenience, or the "food buzz" you get from eating something. It may also be that buying everything based on price and convenience is itself a cultural norm in the U.S.
It might be economic factors as well. If the U.S. is the world leader in corn production and industrial-scale agriculture, the market for food products in the U.S. might just be very different from what exists in Europe.
Finally there is the possibility that the U.S is not alone in the obesity epidemic, merely ahead. I'm not totally sold on that, but it's a possibility.
I'm a Canadian currently living in the US; our two countries are culturally very similar, and diet-wise practically identical (save poutine, sweet sweet poutine). But the obesity epidemic hasn't swept Canada nearly the same way it is commonly seen in the US.
I just got back from a trip to Canada, and I can say with absolute confidence that the typical restaurant dish in the US is more than twice the size it is up north.
It's this way in Asia too, and probably Europe (though I haven't been, shame).
It doesn't matter how much you exercise (or don't), nor does it matter if you're eating steaks vs. granola bars. If you're eating twice as much as the rest of the world, you've got big problems.
The US needs to halve their serving sizes in restaurants, and reduce the appetite of the general population. You can improve what you're eating, and you can exercise more, but none of that will do diddly squat until you cut down on intake.
From: http://www.statcan.gc.ca/pub/82-620-m/2005001/article/adults...
"The racial make-up of the two countries might explain some of the differences, as research has shown that obesity rates vary by ethnic origin. Nonetheless, when obesity rates of White Americans and Canadians are compared, White women in the United States were significantly more likely than those in Canada to be obese: 30.3% versus 24.8%. However, the percentages of White American and Canadian men who were obese did not differ."
Despite it being actually fairly cheap, what arrived, was a MASSIVE batter encrusted mountain of about 50 sandwich quarters...
Good grief America!
"The International Obesity Task Force estimated that Finland, Germany, Greece, Cyprus, the Czech Republic, Slovakia and Malta have exceeded the United States figure of 67% for overweight or obese males."