alt Hacker NewsHistory is a pretty strong indication that it’s clear to me.
I find it exceptionally hard to believe populations at scale went from relatively “normal” weights to obese as the majority due to an emerging novel metabolic disorder. All within 1 to 2 generations.
Much simpler explanation is that diets and lifestyles changed leading towards obesity. Whether or not a metabolic disorder happened somewhere in the middle there seems irrelevant to me. It’s very clear to me that obesity causes the issues and not the other way around.
I’m open to thinking differently about it, I just find the evidence uncompelling as someone who was obese the majority of my adult life. Given the unique circumstances of how I grew up and then later experienced life, I’m quite confident obesity is primarily caused by lifestyle. Put simply - put yourself in a situation where obesity becomes easy to achieve and the majority of people will become obese.
Humans being what they are will of course have myriad of outliers to refute the point, but outliers are uninteresting to discuss in this context.
The problem with this line is that there are populations that live very similar lifestyles but have massively different obesity rates. The rate on obesity in Tonga is much larger than the one in the USA, which is itself much larger than France - and yet all three are modern industrialized nations where the vast majority of the population lead mostly sedentary lifestyles.
Even within these places, there are often huge disparities in obesity rate. For example, Colorado has half the rate of obesity as the USA: are people in Colorado leading such hugely different lives from the rest of the nation? And are people in Colorado leading lifestyles more similar to those in California than those in Kentucky?
To me, the much more plausible explanation is that there is some aspect of modern life (most likely some element in our food, but very possibly in our enviroment as well) that is causing metabolic issues that lead to this huge increase in appetite that in turn leads almost inexorably to obesity.