% of calories from carbs is a robust predictor of overweight prevalence

Also, I wouldn’t say “A correlates with B” (a symmetric relation) implies “A is a predictor of B”.

A food insecure developing country might be overtly reliant on staple carbs like rice and grains. Easy access to protein sources like meat could also just mean easy access to excess calories, regardless of whether a carb heavy diet would otherwise be more predictive of obesity.