[Cthulhu_]

The thing is that what "looks" healthy is culture-dependent; nowadays in the caucasian west, looking lean and tanned is considered a healthy / attractive look, but in other places, times and subcultures having more weight or pale skin is considered healthy (or attractive).

[bawolff]

That doesn't prevent it from correlate. If obesity is the bigger threat than looking skinny is correlated with being healthy. If food scarcity is a bigger threat than the opposite.

However a lot of more subtle things like soft, shiny hair or good skin are correlated with nutrition.