Obesity prevalence by country: https://www.cia.gov/library/publications/the-world-factbook/...

There are both rich and poor countries near the top of the list.

Replying very late, but I've always found it interesting that in poorer countries, obesity can indicate wealth (you have money to overindulge) whereas in richer countries it's often the reverse (poorer people buying sugary/fast food, can't justify a gym membership, etc).

What causality are you implying here? My extended family is all blue collar for the most part and almost all live in the same few small towns. I'm saying, in my blue collar family, the cousins who stayed fit, thin, avoiding alcoholism and smoking look a decade or more younger than those that didn't.

Looking younger does correlate with both wealth and health. But while wealth and obesity are only correlated, there's certainly a casual relationship from obesity to health, and therefore from obesity to looking older.

There is probably a third variable that explains both physical fitness and wealth: education or discipline for instance.

Of course, it is more than one variable. Reality tends to be multidimensional.