French people eat fine cheese, and other fine foods. Americans are fed imitation cheese, and told that it's better for them because it doesn't have 'bad fat'.
The experts call this a "paradox" [1]. I think we're being swindled.
One of the biggest difference is walking. Most cities I've visited in Europe are easily walkable. You can more or less get what you need. People in small and big cities seem to walk much much more.
In Atlanta, this simply isn't possible for most people. We've built out more than up and inhibited public transportation but that's another sorry. Savannah is a much more walkable city similar to places in Europe. I wonder if it's the difference beetween old and new cities.
If I look at obesity by US city [1] it's true that a lot of the top southern cities don't have great public transportation AFAIK, but the greater NYC metro area is relatively high up on the list. And Las Vegas is about tied with Boston and San Francisco.
I suspect eating habits (the US South is notoriously bad in a lot of ways) and poverty have more to do with it than the state of the local public transit system.
[1] https://wallethub.com/edu/fattest-cities-in-america/10532/
Here's an example using some CDC data and based on metro areas [1]. Atlantic City is the worst and Boston is 1% more than Atlanta. It doesn't really support my walkability claim.
http://www.governing.com/gov-data/obesity-rates-by-state-met...
I suspect your gut bacteria are simply unused to the new environment (possibly including the milk). The same kind of thing happens to most people when they travel overseas. As a child I spent most summers in Mexico. Within the first few weeks I would have a bout of serious diarrhea and vomiting, literally every year. But native Mexicans who ate the same things didn’t have the same problem, being well adapted.
Anyway, what specific type of milk are we talking about? Full fat homogenized milk? Skim milk? Unhomogenized milk?
In the German case you might also be talking about UHT milk, which is common in many countries (not sure about Germany) but vanishingly rare in the USA? I think that stuff is awful, YMMV.
There are many different kinds of 'American milk'. A primary difference is what the different farmers feed their cows.
A few years ago I suffered through the History Channel's Modern Marvels episode about cotton. There's a bit towards the about how cottonseed meal (a waste product of the cotton industry) is commonly used as feed for the dairy industry.
Someone commented about how they taste a difference for the week after farmers switch their cows from summer rations to silage -- it takes a week for the cows' bacteria to adjust. I should find that comment & favorite it... Ah, here:
You can always tell when the cows switch
between grass and silage in the spring
and fall. Milk tastes like garbage for a
week or two until they get sorted out.
The usual macronutrient values (9kcal/g fat, 5 kcal/g EtOH, 4kcal/g carbs and protein) are surprisingly decently calibrated for metabolic inefficiencies.
They do not, however, take into account hormonal responses, which are probably quite a bit more important than once assumed. So there's that.