In Nepal, my parents always warned me before eating at some rest stops because they said the food was doctored with baking soda to make you feel fuller, guess it was true after all and not just an urban legend heh.
Totally an urban legend. What do people think Alia seltzer is made from? You know the thing you take to feel better after eating too much?
I've sometimes used baking soda to accelerate softening of beans, and I imagine the effect is more appreciable at higher altitudes perhaps? Some of the usage of baking soda could be innocent enough.
I've heard the same from South Indian friends, so I guess it's pretty widespread.