(OR17-05-25) Changing Entrée Portion Size Labels to Encourage Selection of Smaller Portions When Dining Out: A Randomized Controlled Field Experiment

Objectives: To test the degree to which a portion size labeling intervention influenced consumers to select smaller lunch portions at two large cafés.

Methods: A randomized controlled experiment was conducted at two large, university-based cafés between Jan. and May 2024 during lunch (6-week baseline, 7-week intervention). Cafés newly offered 2 entrée sizes: the new size was half the size of the original and ~30% lower in price. The reduced-sized entrée was called “Small”, and the original was called “Large.” During the intervention period for the intervention café, the reduced size was labeled “Standard”, and the original was called “Large.” Daily transaction data were used to evaluate the primary outcome of average kcal per entrée purchased. Secondary outcomes were: 1) total kcal per transactions with entrees to examine potential compensatory effects from the labeling intervention; 2) total kcal per transactions with entrees by size of entrée, collapsed across café, to examine potential compensation from ordering a reduced size; and 3) historical vs. current sales collapsed across cafes to examine the impact of adding a reduced portion at a lower price. Data were analyzed using linear regression models with a difference-in-differences (DID) framework. Sales data were log transformed to look at percent changes.

Results: During the study period, 2,940 reduced-sized, and 8,587 large entrées were sold. Average kcal per entrée purchased (DID -7.5 kcal [95% CI: -25.8, 10.7]) and average total kcals per transaction (DID -21.6 kcal [95% CI: -46.6, 3.3]) in the labeling intervention café did not differ compared to the control café during the intervention. Participants who ordered a reduced-sized entrée regardless of which café they made the purchase bought 405 fewer kcals (95% CI: -414.7, -396.1) per transaction compared to participants who purchased the original size. Average weekly gross sales increased by 14.8% (95% CI: 9.5, 20.4) in 2024 compared to the same period in 2023 after adjusting for 2024 price increases.

Conclusions: Smaller portions may help people eat fewer calories. While the labeling intervention did not increase purchasing of reduced-sized entrées, we showed that 1) people did not compensate reduced portions with other foods; 2) there is a demand for reduced portions, and 3) it is feasible to offer reduced sizes without negatively impacting sales.

Funding Sources: N/A