Aner Tal, PhD
Aner Tal, PhD, postdoctoral research associate, Food and Brand Lab, Dyson School of Applied Economics and Management, Cornell University, Ithaca, New York. His study was published in JAMA Internal Medicine.
If you’ve ever hit the supermarket when your stomach was rumbling with hunger, you probably bought more food than you otherwise would have. Unless you’re on a strict financial budget, the extra quantity wasn’t much of a problem. But what about the quality of the food you buy when your belly is saying, “Feed me, feed me”? A new study offers interesting insights on how hunger—and the time of day—can really mess up your food choices.
Researchers from Cornell University’s Food and Brand Lab conducted two experiments. For the first experiment, 68 people who hadn’t eaten in five hours arrived at the lab. Half of them were given crackers and told to eat until they were no longer hungry…the other half of the participants were not offered a snack.
Next, all participants “went shopping” in a simulated online grocery store. They were invited to buy whatever they wanted, with no spending limit and no prices shown. The selections included various lower-calorie foods (fruits, vegetables, chicken breasts) and higher-calorie foods (candy, salty snacks, red meat). Each high-calorie food had a low-calorie alternative.
What the virtual shoppers bought: Compared to the participants who had eaten before shopping, the hungry participants “bought” 19% more food overall—including 6% more of the low-calorie foods and 45% more of the high-calorie foods.
The second experiment took place in a real grocery store with real shoppers, where the researchers evaluated the contents of shopping carts to determine what was purchased at different times of the day, comparing the ratio of low-calorie to high-calorie foods. Previous research had showed that shoppers are most likely to be full between 1:00 pm and 4:00 pm (just after lunch) and most likely to be hungry between 4:00 pm and 7:00 pm (before dinner), so these were the two time frames that were compared.
What the real-life shoppers bought: Again, hungry shoppers bought more high-calorie foods than non-hungry shoppers did. But where the hungry evening shoppers really fell down was in spurning the low-calorie options, selecting 36% less of these than the nonhungry shoppers did.
Why we shop the way we do: Previous laboratory research using brain scans showed that when hungry people looked at pictures of high-calorie foods, their brains really lit up—specifically, the amygdala and other “reward” centers in the brain. This new study provides real-life evidence that hunger affects how appealing various foods seem…and that the way our brains react to different foods can lead us to shop differently and to buy less healthful food when our stomachs are empty.
Our longest fast typically occurs overnight, but few people go grocery shopping first thing in the morning, before eating any breakfast. The predinner rush hour, however, is another story. Many people dash to the market on the way home from work or after wrapping up a long afternoon of errands, which typically is hours after their midday meal.
Smart move: To make it easier to follow a healthful food plan, don’t go to the supermarket right before mealtime. If you must shop on your way home from work or at other times when you’re likely to be hungry, grab a nutritious snack—some nuts, a piece of fruit—and eat it before entering the store.
