It is well known that buying food when one is hungry is a total recipe for a disaster.

In two upstate New York elementary schools, students use an electronic pre-ordering system to order lunch in the morning. Fourteen teachers agreed to enroll their classes in a four-week study to test the effects of pre-ordering lunch. These classrooms were randomly assigned to one of three experimental conditions: 1) stop preordering for the 3rd week and resume for the 4th week, 2) stop preordering for the 4th week, or 3) continue preordering for all four weeks.
What did the sales records report? A significant number of healthier choices were made when students pre-ordered lunch. When preordering was available, 29.4% of students ordered the healthier lunch entrée compared to 15.3% when no preordering took place. When ordering in the lunch line, hunger mixed with the aromas and sight of unhealthy foods won out in spontaneous food decisions: healthy entrée selection was reduced by 48% and less healthy entrée choices increased by 21%.
Further details on the study
This is great news! In school, preordering can help students make healthier choices in entrées. Simply by changing the decision environment, students were nudged to select healthier entrées. Even though schools in this study used an electronic pre-ordering system, paper-based systems can be just as effective, and less costly. Either system provides an effective method to help students make more health conscious decisions at lunch.
Source-Eurekalert