The researchers say their findings suggest that the taxes were more effective than subsidies. This conclusion doesn't surprise Karlan. He sites the theory of loss aversion: "People are just more responsive to price increases than decreases."
Karlan says a "sin tax" — charging more for unhealthful foods — would not change families' diets or approach to nutrition overnight. But it could serve as a first step in raising awareness of bad habits, alerting us to the kinds of things we choose to snack on.
