As someone who immigrated from France to the US, it’s pretty obvious why people in the US are obese: people don’t know / don’t have the time to know how to eat properly and eat junk food, all the time, at any hour, and don’t move around. It’s pretty obvious when you realize that there is a lot less overweight people in upper middle class areas.
When did you do that? In last twenty years France has become one of the fattest countries in Europe. I was there in 2008 and 2019. Huge difference.
The upper middle class in USA is fatter than it used to be. Very few people actually lean as opposed to having much less fat. The class disparity is real but not the only explanation.
2014, I still go back annually. You have a large portion of the lower middle class that’s more overweight now but it’s not like in the US where you can be somewhere where it’s impossible to find healthy food for 100 miles, and where you can go inside a Walmart and almost everyone is overweight. There’s obviously some bias given I live in the Bay Area, I’m sure there are areas where upper middle class folks are more overweight.
even among people who say what you're saying - there's just so many things that raise insulin levels or contribute to insulin-resistance.
people assume it's sugar. and a lot of it is and it's the first thing people should cut back on.
but people are surprised zero-calorie artificial sweeteners and crystalized versions of stevia and monk fruit do.
people aren't even aware that omega6s PUFAs (which we're supposed to have a 1:1 ratio with omega3s, and are supposed to have both in fairly low levels) also impact insulin resistance
activity does, sleep does, things impact it positively like a wide range of plant foods or teas.
but more simply - without going into the whys or the science, if generally speaking people cut out A. Sugar and B. processed foods (thus removing a ton of salt and omega6s) people would be a million times better off.
It may be a contributor but there are so many "obvious" things that cause obesity in the modern world that a paper needs really strong arguments with a rigorous statistical analysis with confounding factors in order to draw conclusions.
The obvious include: high availability of energy-rich, cheap food, lower amount of physical activity, food designed to be addictive (usually with lots of sugar),...
There is also a strong correlation between obesity and low socioeconomic status, that can be also explained by "obvious" factors, like irregular meals, less physical activity, cheap, energy-rich, nutrient-poor food and poor education regarding healthy habits.
There appears to be a similar issue with other endocrine disruptor chemicals like phthalates (plastic softeners) possibly increasing the risk of obesity. But those are typically polluting food rather than air.
