Traffic-Light Labels and Choice Architecture

Background

Preventing obesity requires maintenance of healthy eating behaviors over time. Food labels and strategies that increase visibility and convenience of healthy foods (choice architecture) promote healthier choices, but long-term effectiveness is unknown.

Purpose

Assess effectiveness of traffic-light labeling and choice architecture cafeteria intervention over 24 months.

Design

Longitudinal pre–post cohort follow-up study between December 2009 and February 2012. Data were analyzed in 2012.

Setting/participants

Large hospital cafeteria with a mean of 6511 transactions daily. Cafeteria sales were analyzed for (1) all cafeteria customers and (2) a longitudinal cohort of 2285 hospital employees who used the cafeteria regularly.

Intervention

After a 3-month baseline period, cafeteria items were labeled green (healthy); yellow (less healthy); or red (unhealthy) and rearranged to make healthy items more accessible.

Main outcome measures

Proportion of cafeteria sales that were green or red during each 3-month period from baseline to 24 months. Changes in 12- and 24-month sales were compared to baseline for all transactions and transactions by the employee cohort.

Results

The proportion of sales of red items decreased from 24% at baseline to 20% at 24 months (p<0.001), and green sales increased from 41% to 46% (p<0.001). Red beverages decreased from 26% of beverage sales at baseline to 17% at 24 months (p<0.001); green beverages increased from 52% to 60% (p<0.001). Similar patterns were observed for the cohort of employees, with the largest change for red beverages (23%–14%, p<0.001).

Conclusions

A traffic-light and choice architecture cafeteria intervention resulted in sustained healthier choices over 2 years, suggesting that food environment interventions can promote long-term changes in population eating behaviors.

Introduction

The rising prevalence of overweight and obesity is now a major health concern in the U.S. and worldwide.1, 2 Easily accessible, low-cost, energy-dense food contributes to high-calorie diets and weight gain.3, 4 Although individual-level interventions can result in large weight changes among small groups of patients, efforts to prevent obesity at the population level will require changes in the food environment that promote healthy, lower-calorie foods and discourage unhealthy, energy-dense foods.3, 4

Several factors contribute to unhealthy eating patterns, including lack of knowledge,5, 6 automatic or habitual choice processes,7, 8 and preference for convenience.9, 10, 11 All of these factors can be addressed in the context of the food environment. Nutrition labeling on food packages addresses knowledge by providing detailed information about the nutritional and caloric content of a food, but many nutrition labels require a high level of literacy and numeracy to interpret.¹² Simpler labeling schemes, such as traffic lights that identify healthy items as “green” and unhealthy items as “red,” have demonstrated effectiveness for promoting healthier choices in studies with either brief exposure conditions or short-term follow-up.13, 14, 15, 16, 17, 18 “Nudging strategies” that target automatic processes and preferences for convenience can manipulate the food environment to promote healthier choices.⁷ Some studies have demonstrated that small changes in the food environment, including choice architecture interventions to make healthy items more visible and convenient, can result in better food choices, but these studies have demonstrated only short-term change after a brief exposure to the intervention.9, 10, 13, 14, 19, 20

It is critical to evaluate the long-term effectiveness of food environment interventions in order to develop effective health policies and programs for obesity prevention. A simulation modeling study of a traffic-light intervention demonstrated that if small changes in energy consumption were sustained at a population level over time, the intervention would be effective for both weight reduction and cost savings.²¹ However, it is currently unknown if food labeling and environment interventions can produce durable changes in healthy food choices or if individuals revert back to unhealthy eating patterns.

It has been previously demonstrated that a traffic-light labeling and choice architecture intervention in a large hospital cafeteria was effective for promoting healthy food and beverage choices over 6 months among all cafeteria patrons and among hospital employees.13, 14 The objective of the current study was to evaluate whether the increase in sales of healthier items was maintained over the 24 months following implementation of the intervention by comparing sales at 12 and 24 months to a baseline period prior to the labeling. Outcomes were analyzed for (1) purchases of all cafeteria patrons to determine the effectiveness of the intervention for a broad population of infrequent and frequent cafeteria users and (2) purchases of a cohort of 2285 employees who regularly visited the cafeteria from baseline through the end of a 24-month follow-up to determine the effectiveness of the intervention for customers who had repeated exposure.