I wonder how many calories you get just by breathing. Would location matter? I think it would, because somewhere like a pizza place probably has more microscopic particles of food in the air than somewhere like your house. After all, they deal with a lot more food than your house (unless I’m completely misjudging the average household).
What about places like the forest, where there would be lots of pollen and stuff like that floating around? While that’s not food for us, it would certainly still have calories.
Finally, would it be possible to have a restaurant in which you only “eat” by smelling the food? I guess it’d be possible, but it wouldn’t last long…