Why being eco-conscious doesn't necessarily help your health.

By Real Simple
Updated July 08, 2015
Credit: Jose Luis Pelaez/Getty Images

You probably pat yourself on the back when you remember to bring a reusable tote to the supermarket—you're being an eco-friendly consumer!—but a new study from the American Marketing Association says that same bag may be influencing your shopping habits in some not-so-healthy ways. According to new data published in the Journal of Marketing, shoppers who use reusable totes are more likely to buy organic food, but they also tend to purchase more junk food.

Using loyalty card data from a grocery store chain located in California between May 2005 and March 2007, researchers from Harvard and Duke business schools compared purchases made by those who brought their own bags with the transactions of those who did not. Another group of people recruited from an online pool were randomly assigned to one of two scenarios—bringing a reusable bag or using bags provided by the store. Participants were then presented with a floor plan of the grocery store and asked to list the ten items they were most likely to purchase. In both scenarios participants who brought their own bag were more likely to purchase both organic food and junk food.

"Grocery store shoppers who bring their own bags are more likely to purchase organic produce and other healthy food. But those same shoppers often feel virtuous, because they are acting in an environmentally responsible way,” study authors Uma R. Karmarkar and Bryan Bollinger said in a statement. Translation: Shoppers seem to reward themselves for eco-friendly behaviors with cookies, potato chips, and other junk food.

Researchers did, however, notice one characteristic that seemed to skew shopping patterns: young children. Parents bought less organic food and less junk food, likely because their purchasing preferences defer to their desire to keep kids healthy.