I don’t know the reason, but I can speculate - too many chemicals probably? Every time I am in India, I pig out. Yet, I rarely put on weight. I eat way less (like 50% less) in the U.S, and put on weight easily unless I am super careful.
This is not to say all foods are awesome in India of course. But there is something not right about the quality of food here. Everything seems to be optimized for shelf life, profit, looks and taste, rather than nutrition.
A single mango in my town costs $2.79, it has zero smell and tastes like cardboard. But it doesn’t go bad even after ten days, on the kitchen counter (I mean, outside the refrigerator).