It has long been known that grocery shopping while hungry overpowers dietary caution and sabotages weight loss efforts.
But the dietary killjoys at Cornell University have determined the situation is much worse than we thought. Not only does filling up your food cart while your stomach is empty lead to out of control snacking in the short term, it condemns you to an entire week's worth of unhealthy eating.
The Cornell researchers followed 68 shoppers as they clicked through an online grocery site that offered a mix of healthy choices -- including fruits, vegetables and lean meats -- and unhealthy, high calorie snack foods like candy, chips and soda.
The shoppers who didn't eat for four to five hours before filling their virtual food baskets bought the same number of items as the shoppers who snacked on crackers before clicking away. But the hungry shoppers selected more processed junk foods, 23 percent more on average. A follow up field test where researchers secretly followed shoppers who hadn't eaten for several hours found much the same.
"You don't buy more, but you do buy more of the wrong type of calories," noted Brian Wansink, one of the study's lead investigators and author of the new book, Slim By Design. "You buy things like cereal, snacks, chips, candy and other convenience foods that require no preparation and that you can eat right away."
Previous research demonstrated that fasting for up to 18 hours can drive shoppers to make less diet-friendly choices and spend more cash overall. But this is the first study to show you don't have to be terribly hungry for your judgment to be affected.
Even just a few hours without eating is enough to send you in search of a quick fix to satisfy hunger. And, as Wansink noted, this is often the state shoppers find themselves in as they rush to the market after a long day of work.
Unfortunately, the effect goes well beyond buying a candy bar to tide you over on the drive home, Wansink said. Shoppers who impulsively purchase ready-to-eat, low nutrition foods set themselves up for repeated diet disasters because they fill their pantries with junk instead of healthier fare.
"It ends up cursing the rest of your week because you bought way too much of the convenience foods and not enough of the good stuff. So now there is less healthy food for you to choose from at home."
Americans seem to be snacking more than ever. On average, Americans enjoy 2.3 snacks per day according to the latest poll by the Hartman Group. Nearly 30 percent of people said they snack impulsively while another 17 percent reach for a snack when they don't feel like cooking. Almost 60 percent of respondents said choosing a healthy snack is important to them, yet the two most popular snacks choices are chips and soda.
Wansink said the obvious moral here is don't shop hungry.
"It helps to plan your visit to the supermarket and if you're hungry, eat an apple before you go," he said.