The US certainly has an obesity problem, but there's no way the average American consumes almost 3800 calories a day.
Here's an "average" american diet:
breakfast: bagel with creamcheese = 430 calories
mid-morning latte = 225 calories
lunch:6" subway cold cut sandwich = 410 calories
lunch: small bag chips = 400 calories
mid afternoon kit-kat = 500 calories
dinner: spaghetti and meatballs = 970 calories
12 oz bottle of budweiser = 110 calories
total: 3045 calories
Considering that many americans are going to get the 12" sub, drink more than 1 beer and a bunch of soda, have seconds for dinner, and eat "dessert" every night, it doesn't seem that far-fetched that the average american consumes 3800 calories per day.
Starbucks latte with nonfat milk = 168 calories
http://caloriecount.about.com/calories-starbucks-coffee-caff...
6" Subway Cheesesteak (It was the worst one I could find on browsing) = 360 calories
http://caloriecount.about.com/calories-subway-sandwiches-6-c...
Small bag of Lays potato chips = 150 calories
http://www.dietfacts.com/html/nutrition-facts/frito-lay-lays...
Kit-kat bar = 210 calories
http://caloriecount.about.com/calories-hersheys-kit-kat-milk...
Fazoli's spaghetti and meatballs (Again, the worst I could find) = 720 calories
http://caloriecount.about.com/calories-fazolis-spaghetti-mea...
If you were to add in an extra large vanilla shake from McDonald's you'd add a quick 1100 calories to your day.
http://www.brueggers.com/documents/nutrition.pdf
Subway value was from the "Cold Cut Combo":
http://www.subway.com/subwayroot/menunutrition/nutrition/pdf...
(Note that Subway's page says the cheesesteak sub you mention is 520 calories, not 360.)
spaghetti and meatballs value was from here http://www.calorieking.com/foods/calories-in-italian-spaghet...
I did inflate the potato chips, I thought the small bag was 3oz, not 1oz. Also I thought the kit kat was per bar.
3800 calories is still only a little bit of work. Most people I know drink 2 lattes, 2 or more beers, and would consider the 6" sub the "diet" option.
As was mentioned by someone else, if the average American ate 3800 calories a day they would continually gain weight until they reached the equilibrium point of maintenance calories.
The average height of America males is 5'10". http://en.wikipedia.org/wiki/Human_height
The average weight of American males is 191lbs. http://en.wikipedia.org/wiki/Body_weight
Given those numbers, and an age of 35 years, with a base metabolic rate, calorie maintenance is 1809kcal/day and 2488kcal/day for exercise 3 times/week (surely more than the "average" American) http://www.freedieting.com/tools/calorie_calculator.htm
The equilibrium point for 3800kcal/day and 3 times/week exercise is 400 pounds!
Methinks you're still fudging the numbers.
I was personally enlightened, at least.
Basically in the 45 years when your calorific consumption should be the maximum between ~18 and ~60+, you would gain around 8 tons of body weight.
I'm sorry, I love taking a shot at America for the obesity problem, but an 8 ton man? Really? Did the people who wrote that study even think that figure through? They factored in imports/exports, but they didn't bother to even guesstimate a percentage for food actually consumed in a household.
Also you have to look at the level of activity. An athlete or construction worker can probably eat 3800 calories every day and not gain weight.
My problem with calorific calculations, and even bodyweight averages in themselves is that they're so bogus. Post-war diets are vastly different than our current diets. The factors that effect body weight are also vastly different, I'm sorry but we've got thousands of medicines that weren't available 50 years ago, and one of the major contributing factors to weight loss is disease.
Americas weight problem isn't going to be resolved by figures and statistics, and it's certainly going to be hurt by poor statistics like those provided in the study in question.
How can a 190lb average American Joe consume 3800 calories working an Average sedentary job not be gaining a pound of body fat per week? The figures are ludicrously disjointed.
I understand that everybody is different, believe me I work in construction, I likely eat a thousand calories more than I'm recommended and I'm presently losing weight. My BMI says I'm going to drop dead, my vitals tell a different story. My heart is a near-perfect metronome when at rest (literally ~60 bpm), my body fat on my limbs is exceptionally low (especially my legs due to lots of moving heavy weights).
When I'm told I'm obese because of some voodoo astrology bodyweight index by a doctor who's showing all the signs of high blood pressure and could stand to lose a good 10 index points himself, I don't listen and in 20 years down the line I still won't be listening to the new doctor who's taken over the dead guys office because he'll be well on his way to rosy red cheeks and shortness of breath from picking up a tongue depressor.
Governments are paying for these studies that are providing sheer utter crap and they're trying to resolve weight issues by indirect action and instructing their overweight medical professionals to tell their patients to lose weight.
Here's my very simple solution: Vehicle free down towns nationwide. Not only will it be phenomenal for the environment (air quality, noise pollution, etc.) and provide a boon for public transit infrastructures, but it will also mean everyone is forced to get at least some exercise in during a work day.