There are plenty of rules for the ideal grocery shopping trip—you know, the kind where you buy more than just Pop-Tarts and Fritos. Don’t shop hungry. Make a list. And now? Eat an apple. 

A new study in the journal Psychology and Marketing by Cornell University’s Food and Brand Lab finds that eating an apple sample before grocery shopping encourages people to buy more fruits and vegetables. In one test, the researchers gave 120 shoppers a piece of apple, a cookie, or no sample at all when they entered a grocery store. The shoppers who ate an apple bought 25 percent more fruits and vegetables than the no-sample group, and 28 percent more than the cookie eaters. 

The results were then replicated virtually in a lab. First, 56 people were given a cookie or an apple sample, then told to imagine a grocery trip. When shown 20 different product pairs of foods they might purchase, the participants who ate the apple tended to choose lower-calorie products. 

The connection between healthy eating and healthy purchasing behavior is all about perception. In a third test, volunteers were either given chocolate milk labeled “healthy” and “wholesome” or the same chocolate milk labeled “rich” and “indulgent.” Those who received the “healthy” milk chose more healthy foods in a virtual grocery trip, compared to those who thought they were indulging. 

So if you want to resist those endless aisles of Cap’n Crunch and chocolate-covered everything, arm yourself with healthy snacks ahead of time. Or just slap a label on your chocolate milk that reads "Super Healthy Food Product."