The impact of price discounts and calorie messaging on beverage consumption: a multi-site field study.

Objectives: To examine the efficacy of alternative approaches for shifting consumers toward zero calorie beverages. We examined the effect of price discounts and novel presentations of calorie information on sales of beverages.

Methods: This prospective interrupted time-series quasi-experiment included three sites in Philadelphia, PA, Evanston, IL, and Detroit, MI. Each site received five interventions: (1) a 10% price discount on zero-calorie beverages; (2) the 10% discount plus discount messaging; (3) messaging comparing calorie information of sugared beverages with zero-calorie beverages; (4) messaging comparing exercise equivalent information; and (5) messaging comparing both calorie and exercise equivalent information. The main outcome was daily sales of bottled zero-calorie and sugared beverages. Data was collected from October 2009 until May 2010 and analyzed from May 2010 until May 2011.

Results: The overall analysis failed to demonstrate a consistent effect across all interventions. Two treatments had statistically significant effects: the discount plus discount messaging, with an increase in purchases of zero calorie beverages; and the calorie messaging intervention, with an increase in purchases of sugar-sweetened beverages. Individual site analysis results were similar.

Conclusions: The effects of price discounts and calorie messaging in different forms on beverage purchases were inconsistent and frequently small.