Where you said "likely", I think you meant "speculative".

As with most nutritional information, "it's complicated" - but to suggest that there is a well demonstrated that high carbohydrate diets and plant based proteins [1] has implications for heart disease won't hold.

Also [1]: why do you say low protein? Might just be my ignorance, but I would expect fairly high protein content from all the common dal, channa, etc. dishes.

To be clear, I'm not saying that there isn't a dietary connection - but to say it is as simple as "carbohydrates bad, protein bad" is at best premature, but more likely just inept.

edit: I shouldn't have kept the parents "high carbohydrate" language intact, as that's actually another question - is the Indian diet meaningfully "high carbohydrate" ?