One famous experiment compared "usage volume" of cooking oil, spaghetti, and M&Ms.
Subjects poured 22% more oil, 23% more spaghetti, and 52% more M&Ms from their respective larger containers (vs. small ones).
So when you buy that next giant sack of food at a big box discount store, unless the by weight savings is greater than roughly 25%, you might well not be saving yourself any money, and you'll almost certainly be adding to your unconscious/mindless eating.
