Package size reliably predicts how much you’ll eat, independent of hunger. Research by Hollands in the Cochrane review found larger portions and packages consistently increase consumption. Zlatevska’s meta-analysis showed doubling portion size increases intake by 35%. The container becomes the unit, and we tend to finish units. The solution: buy small packages, pre-portion large ones, never eat from the original container, create friction for refills.
This companion covers the research, why this happens (unit bias, no stopping point), and the environment fix. (4 min read)