Supermarket discounts of low-energy density foods: effects on purchasing, food intake, and body weight

Abstract

Objective: To assess the effects of a 50% discount on low-energy density (ED) fruits and vegetables (F&V), bottled water, and diet sodas on shoppers' purchasing, food intake, and body weight.

Design and methods: A randomized, controlled trial was conducted at two Manhattan supermarkets, in which a 4-week baseline period (no discounts) preceded an 8-week intervention period (50% discount), and a 4-week follow-up period (no discounts). Twenty-four hour dietary recall, as well as body weight and body composition measures were obtained every 4 weeks. Participants (n = 47, 33f; 14m) were overweight and obese (BMI ≥ 25) shoppers.

Results: Purchasing of F&V during intervention was greater in the discount group than in the control group (P < 0.0001). Purchasing of these items by the discount group relative to the control group during follow-up was reduced from intervention (P = 0.002), but still remained higher than during baseline (P = 0.01), indicating a partially sustained effect. Intake of F&V increased from baseline to intervention in the discount group relative to the control group (P = 0.037) and was sustained during follow-up. Body weight change did not differ significantly between groups, although post hoc analysis indicated a change within the discount group (-1.1 kg, P = 0.006) but not within the control group.

Conclusions: Discounts of low-ED F&V led to increased purchasing and intake of those foods.