MONDAY, May 6, 2013 (HealthDay News) -- People who grocery shop when hungry tend to load up their carts with higher-calorie foods and more of them, a new study suggests.
Not only does that affect the meal they will be eating at home that night, but their meals throughout the week, according to researchers Brian Wansink and Aner Tal, with the Food and Brand Lab at Cornell University.
"It's known that hungry people buy more food in the grocery store, but what happens more is that people shift their shopping patterns to contain more high-calorie foods," Tal said. "When you are hungry, you think high-calorie food can provide you with more energy."
Dieting by skipping meals might not be a good idea, Tal added. If you shop while hungry you might wind up compensating for it with the high-calorie foods that will make up meals for the next several days, he said.
Candy, salty snacks and red meat were deemed higher-calorie foods in the study. Meanwhile, fruits, vegetables and chicken breasts counted as lower-calorie choices.
Tal is now investigating whether having a snack before food shopping will tip the scale toward choosing lower-calorie foods.
The report was published as a research letter in the May 6 online edition of JAMA Internal Medicine.
Another expert explained what might be driving the urge to shop for calorie-rich foods.
"Your body does not know the difference between purposely depriving yourself of food, as in fasting or dieting, or a lack of food or a famine," said Samantha Heller, a senior clinical nutritionist at the NYU Langone Medical Center, in New York City. "Your body does not know there are grocery stores and that you can have pizza delivered 24/7. The human body has not evolved as quickly as our agriculture or technology. It thinks we still have to go out and catch breakfast."
Therefore, she said, when the body is deprived of food it goes into survival mode because it does not know when there will be another meal.
"This complex defensive response affects both psychological and physiological parameters. When you do start choosing and eating foods, the body directs you to go for high-calorie foods to replace calories lost and to store up in case of another famine," Heller said.
To make their point, the researchers did two experiments. The first was a lab experiment in which people were told not to eat five hours before the study.
Before the test began, some of the 68 participants were given crackers to appease their hunger. Then, they all were asked to "shop" in a simulated, online grocery store. Hungry people tended to choose higher-calorie foods such as regular ice cream over low-fat ice cream, the researchers found.
In a second study, the researchers followed 82 actual shoppers during the course of the day at times when they were most likely to be full or hungry.
Again, Wansink and Tal found that hungry shoppers bought more high-calorie products, compared to shoppers who weren't hungry.
Nutritionist Heller said this very small study indicates that skipping meals, fasting and restrictive dieting, even for short periods of time, is likely to backfire if weight loss is the goal.
It is important to eat at relatively regular intervals, she added. "This signals the body that fuel is readily available. Metabolism can run at optimal levels. Energy is available for biological functions and daily activities," Heller explained. "The immune system has the wherewithal to keep the body healthy. Mood improves," she said.
"Choosing healthy foods, eating regularly, monitoring portions and getting in daily exercise is the best way for your body and mind get happier and healthier," Heller advised.
For more tips on healthful eating, visit the U.S. Department of Agriculture.