They are.
"Obesity in India has reached epidemic proportions in the 21st century, with morbid obesity affecting 5% of the country's population" [1]. (It's about 7% in America [2].) Meanwhile in China, "the incidence of overweight and obesity among school-age children...was 15.5% in 2010, rising to 24.2% in 2019 and soaring to 29.4% in 2022" [2]. Same story in Vietnam: "The prevalence of overweight among children aged under 5 years increased from 5.6% in 2010 to 7.4% in 2019. For overweight and obesity among children aged 5 to 19 years, prevalence rose from 8.5% and 2.5% in 2010 to 19% and 8.1% in 2020, respectively" [3].
The only country you're right about is Japan, though overweightness is growing there, too [4]. Same across Africa [5].
There is absolutely a systemic effect causing obesity to rise worldwide. That doesn't remove individual agency from the equation. But it's sort of like the opiate crisis: you can have both flawed individual decisionmaking and a systemic bias that fixes the dice while offering more rolls.
[1] https://en.wikipedia.org/wiki/Obesity_in_India
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10357130/
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9947684/
[4] https://www.japantimes.co.jp/news/2024/08/28/japan/science-h...