I think stevoski meant "How do you explain [the relative health and sustained society of] the 500 million vegetarians in India [despite the negative health consequences of vegetarianism]?"

So your "religious ignorance" answer is kinda a flippant one.

I was trying to explain how that diet is sustained.

As for the "relative health" I don't think there's much to begin with to explain. Where did the parent saw it?

A quick search for "Indian life expectancy" puts it at 66 years, vs 78 for the US and 74 for China (results for 2012).

Diet of course is not the only factor in this, but it plays a role, and the numbers don't seem very "relatively healthy" to me. Are there other numbers people can point to to qualify the "relative health" point?

If we mean "relatively healthy" compared to a diet heavy in sugars, HFCS, sodium etc, with obesity like that in parts of the US (South, midwest etc), it might be better -- but that's a pretty low bar.

The correct comparison to perform would be with a stable diet that includes fruits, vegetables et al PLUS meat and fish.