Case Study

A Simple Prompt to Reduce Calorie Intake


Consumers report that they often overeat, and would be happy to receive smaller portions in restaurants. However, it is extremely rare for restaurant patrons to explicitly request a smaller meal.


We invited customers of the Chinese fast food restaurant Panda Express to order a smaller portion of their side dish – for either no discount or a nominal discount. We compared this intervention with the addition of calorie labels and measured the likelihood of downsizing as well as the actual caloric intake of meals.


While calorie labels had no effect on decreasing the amount of calories that customers ordered and subsequently ate, a simple prompt from the restaurant server (“would you like a half portion of your side dish?”) led to up to a third of customers accepting the offer. Those who accepted the offer ate at least 200 fewer calories than those who did not. Downsizing was not only embraced by consumers, but also led to healthier consumption decisions. There was no perceptible difference in consumption when a small or no discount was offered.

Why it matters

While restaurant trends have increasingly moved in the direction of supersizing, there is demand from consumers to reverse the effect and begin downsizing their meals. Coupled with the fact that there has been little to no observable impact on calorie consumption from calorie labeling in fast-food and chain restaurants (implying that consumers rarely downsize on their own volition, even when information is provided), these findings highlight the potential for portion-control interventions that specifically activate consumers’ self-control.

More Information

The authors of this article are Janet Schwartz, Jason Riis, Brian Elbel, and Dan Ariely.

Article in the Health Affairs Journal.