Dan Ariely tested out an alternative to posting calorie counts at fast food restaurants – simply asking customers if they'd like to downsize their side dishes:
We carried out this intervention before and after calorie labels were put in place, and found that while calorie labels had no effect on the number of calories consumed, the offer to downsize did! As much as a third of the customers who were given the offer decided to take less food (compared to ~1% who asked to downsize on their own) and consequently ate less (yes, we even weighed their leftovers), showing that a simple offer to downsize can go a long way toward encouraging a healthier diet. The conclusion: Offering people a chance to exercise self control can be effective, but we need to stop people, slow them down and offer them to take a better path at the moment when they are placing their order.
The Dish 